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Background: The use of thiazolidinediones (TZDs) has been associated with increased fracture risks. Our aim was to estimate the risk of fracture with TZDs in three different healthcare registries, using exactly the same study design, and to perform an individual patient data meta-analysis of these three studies.

Methods: Population-based cohort studies were performed utilizing the British General Practice Research Database (GPRD), the Dutch PHARMO Record Linkage System (RLS), and the Danish National Health Registers. In all three databases, the exposed cohort consisted of all patients (aged 18+) with at least one prescription of antidiabetic (AD) medication. Cox proportional hazards models were used to estimate hazard ratios (HRs) of fracture. The total period of follow-up for each patient was divided into periods of current exposure and past exposure, with patients moving between current and past use.

Results: In all three registries, the risk of fracture was increased for women who were exposed to TZDs: HR 1.48 (1.37–1.60) in GPRD, HR 1.35 (1.15–1.58) in PHARMO, and HR 1.22 (1.03–1.44) in Denmark. Combining the data in an individual patient data meta-analysis resulted, for women, in a 1.4-fold increased risk of any fracture for current TZD users versus other AD drug users [adj. HR 1.44 (1.35–1.53)]. For men, there was no increased fracture risk [adj. HR 1.05 (0.96–1.14)]. Risks were increased for fractures of the radius/ulna, humerus, tibia/fibula, ankle, and foot, but not for hip/femur or vertebral fractures. Current TZD users with more than 25 TZD prescriptions ever before had a 1.6-fold increased risk of fracture compared with other AD drug users [HR 1.59 (1.46–1.74)].

Conclusion: In this study, we consistently found a 1.2- to 1.5-fold increased risk of fractures for women using TZDs, but not for men, across three different healthcare registries. TZD users had an increased risk for fractures of the extremities, and risks further increased for prolonged users of TZDs.

Clinical evidence indicates that bone status is affected in patients with type 2 diabetes mellitus (T2DM). Regardless of normal or even high bone mineral density, T2DM patients have increased risk of fractures. One class of antidiabetic drugs, thiazolidinediones (TZDs), causes bone loss and further increases facture risk, placing TZDs in the category of drugs causing secondary osteoporosis. Risk factors for development of TZD-induced secondary osteoporosis are gender (women), age (elderly), and duration of treatment. TZDs exert their antidiabetic effects by activating peroxisome proliferator-activated receptor-γ (PPAR-γ) nuclear receptor, which controls glucose and fatty acid metabolism. In bone, PPAR-γ controls differentiation of cells of mesenchymal and hematopoietic lineages. PPAR-γ activation with TZDs leads to unbalanced bone remodeling: bone resorption increases and bone formation decreases. Laboratory research evidence points toward a possible separation of unwanted effects of PPAR-γ on bone from its beneficial antidiabetic effects by using selective PPAR-γ modulators. This review also discusses potential pharmacologic means to protect bone from detrimental effects of clinically used TZDs (pioglitazone and rosiglitazone) by using combinational therapy with approved antiosteoporotic drugs, or by using lower doses of TZDs in combination with other antidiabetic therapy. We also suggest a possible orthopedic complication, not yet supported by clinical studies, of delayed fracture healing in T2DM patients on TZD therapy.

Thiazolidinediones (TZDs) are synthetic PPARγ (peroxisome proliferator-activated receptor gamma) agonists and a class of drugs for diabetes mellitus type 2 that can decrease blood sugar efficiently by enhancing insulin sensitivity. However, increased bone fracture risk in diabetic individuals treated with TZDs is one of the reported side effects. Recent studies show that TZDs such as rosiglitazone simultaneously inhibit osteoblast differentiation and activate osteoclast differentiation, leading to bone loss due to decreased bone formation and increased bone resorption. Furthermore, TZDs may activate PPARγ in tissues other than bone, such as the hypothalamus-pituitary-gonad (HPG) axis to indirectly regulate bone mass. This paper will focus on current new developments that implicate potential mechanisms for how PPARγ modulates skeletal homeostasis and how TZDs exert bone-loss side effects.

Background

Diffusion of new drugs in the health care market affects patients' access to new treatment options and health care expenditures. We examined how a new drug class for diabetes mellitus, thiazolidinediones (TZDs), diffused in the health care market in Taiwan.

Methods

Assuming that monthly hospital prescriptions of TZDs could serve as a micro-market to perform drug penetration studies, we retrieved monthly TZD prescription data for 580 hospitals in Taiwan from Taiwan's National Health Insurance Research Database for the period between March 1, 2001 and December 31, 2005. Three diffusion parameters, time to adoption, speed of penetration (monthly growth on prescriptions), and peak penetration (maximum monthly prescription) were evaluated. Cox proportional hazards model and quantile regressions were estimated for analyses on the diffusion parameters.

Results

Prior hospital-level pharmaceutical prescription concentration significantly deterred the adoption of the new drug class (HR: 0.02, 95%CI = 0.01 to 0.04). Adoption of TZDs was slower in district hospitals (HR = 0.43, 95%CI = 0.24 to 0.75) than medical centers and faster in non-profit hospitals than public hospitals (HR = 1.79, 95%CI = 1.23 to 2.61). Quantile regression showed that penetration speed was associated with a hospital's prior anti-diabetic prescriptions (25%Q: 18.29; 50%Q: 25.57; 75%Q: 30.97). Higher peaks were found in hospitals that had adopted TZD early (25%Q: -40.33; 50%Q: -38.65; 75%Q: -32.29) and in hospitals in which the drugs penetrated more quickly (25%Q: 16.53; 50%Q: 24.91; 75%Q: 31.50).

Conclusions

Medical centers began to prescribe TZDs earlier, and they prescribed more TZDs at a faster pace. The TZD diffusion patterns varied among hospitals depending accreditation level, ownership type, and prescription volume of Anti-diabetic drugs.

Aims/hypothesis

Current drug labels for thiazolidinediones (TZDs) warn of increased fractures, predominantly for distal fractures in women. We examined whether exposure to TZDs affects hip fracture in women and men and compared the risk to that found with other drugs used in diabetes.

Methods

Using a nationwide database of prescriptions, hospital admissions and deaths in those with type 2 diabetes in Scotland we calculated TZD exposure among 206,672 individuals. Discrete-time failure analysis was used to model the effect of cumulative drug exposure on hip fracture during 1999–2008.

Results

There were 176 hip fractures among 37,479 exposed individuals. Hip fracture risk increased with cumulative exposure to TZD: OR per year of exposure 1.18 (95% CI 1.09, 1.28; p = 3 × 10−5), adjusted for age, sex and calendar month. Hip fracture increased with cumulative exposure in both men (OR 1.20; 95% CI 1.03, 1.41) and women (OR 1.18; 95% CI 1.07, 1.29) and risks were similar for pioglitazone (OR 1.18) and rosiglitazone (OR 1.16). The association was similar when adjusted for exposure to other drugs for diabetes and for other potential confounders. There was no association of hip fracture with cumulative exposure to sulfonylureas, metformin or insulin in this analysis. The 90-day mortality associated with hip fractures was similar in ever-users of TZD (15%) and in never-users (13%).

Conclusions/interpretation

Hip fracture is a severe adverse effect with TZDs, affecting both sexes; labels should be changed to warn of this. The excess mortality is at least as much as expected from the reported association of pioglitazone with bladder cancer.

Background

Studies have associated thiazolidinedione (TZD) treatment with cardiovascular disease (CVD) and questioned whether the two available TZDs, rosiglitazone and pioglitazone, have different CVD risks. We compared CVD incidence, cardiovascular (CV) and all-cause mortality in type 2 diabetic patients treated with rosiglitazone or pioglitazone as their only TZD.

Methods

We analyzed survey, medical record, administrative, and National Death Index (NDI) data from 1999 through 2003 from Translating Research Into Action for Diabetes (TRIAD), a prospective observational study of diabetes care in managed care. Medications, CV procedures, and CVD were determined from health plan (HP) administrative data, and mortality was from NDI. Adjusted hazard rates (AHR) were derived from Cox proportional hazard models adjusted for age, sex, race/ethnicity, income, history of diabetic nephropathy, history of CVD, insulin use, and HP.

Results

Across TRIAD’s ten HPs, 1,815 patients (24%) filled prescriptions for a TZD, 773 (10%) for only rosiglitazone, 711 (10%) for only pioglitazone, and 331 (4%) for multiple TZDs. In the seven HPs using both TZDs, 1,159 patients (33%) filled a prescription for a TZD, 564 (16%) for only rosiglitazone, 334 (10%) for only pioglitazone, and 261 (7%) for multiple TZDs. For all CV events, CV and all-cause mortality, we found no significant difference between rosiglitazone and pioglitazone.

Conclusions

In this relatively small, prospective, observational study, we found no statistically significant differences in CV outcomes for rosiglitazone- compared to pioglitazone-treated patients. There does not appear to be a pattern of clinically meaningful differences in CV outcomes for rosiglitazone- versus pioglitazone-treated patients.

Context.

The use of thiazolidinediones (TZDs) in patients with type-2 diabetes mellitus appears to be associated with an increased risk of myocardial infarction (MI) compared with placebo or other oral antidiabetic drug regimens.

Objective.

We conducted a study to investigate whether there was a difference in the risk of acute MI and hemorrhagic and non-hemorrhagic stroke between specific TZDs, namely rosiglitazone maleate (Avandia) and pioglitazone (Actos), and other oral antidiabetic agents in a high-risk, largely underrepresented and largely minority Medicaid population.

Study Design, Setting, and Patients.

We analyzed patient encounter data using propensity-scoring methods and logistic regression to compare the risk of cardiovascular (CV) events in patients with type-2 diabetes in a high-risk population.

Main Outcome Measures.

Outcomes were identified through International Classification of Disease (ICD-9) codes 410–411 for acute MI; 430–438 for stroke; and revenue (emergency department) codes 450–459 in the case of MI.

Results.

Using retrospective medical encounter and prescription data analyses, we found that rosiglitazone, compared with other oral antidiabetic agents, was associated with an increased rate of CV events by 20% in a high-risk cohort of diabetic patients. Neither pioglitazone nor the TZD drug class as a whole was associated with an increased CV risk.

Conclusion.

Rosiglitazone was associated with a significant increase in CV events (MI and stroke) among high-risk patients with type-2 diabetes, whereas pioglitazone was not. We recommend further research to capture risk factors that were not observed in our encounter data.

Patients with multiple sclerosis (MS) may be at an increased risk of fracture owing to a greater risk of falling and decreased bone mineral density when compared with the general population. This study was designed to estimate the relative and absolute risk of fracture in patients with MS. We conducted a population-based cohort study using data from the UK General Practice Research Database linked to the National Hospital Registry (1997–2008). Incident MS patients (n = 5565) were matched 1:6 by year of birth, sex, and practice with patients without MS (controls). Cox proportional-hazards models were used to derive adjusted hazard ratios (HRs) for fracture associated with MS. Time-dependent adjustments were made for age, comorbidity, and drug use. Absolute 5- and 10-year risks of fracture were estimated for MS patients as a function of age. Compared with controls, MS patients had an almost threefold increased risk of hip fracture [HR = 2.79, 95% confidence interval (CI) 1.83–4.26] and a risk of osteoporotic fracture that was increased 1.4-fold (HR = 1.35, 95% CI 1.13–1.62). Risk was greater in patients who had been prescribed oral/intravenous glucocorticoids (GCs; HR = 1.85, 95% CI 1.14–2.98) or antidepressants (HR = 1.79, 95% CI 1.37–2.35) in the previous 6 months. Absolute fracture risks were low in younger MS patients but became substantial when patients were older than 60 years of age. It is concluded that MS is associated with an increased risk of fracture. Fracture risk assessment may be indicated in patients with MS, especially those prescribed GCs or antidepressants. © 2011 American Society for Bone and Mineral Research

Background

Thiazolidinediones (TZDs), rosiglitazone (RGZ) and pioglitazone (PGZ) are widely used as hypoglycemic drugs in patients with type 2 diabetes mellitus. The aim of our study was to investigate the profile of adverse drug reactions (ADRs) related to TZDs and to investigate potential risk factors of these ADRs.

Methods

Type 2 diabetic patients were identified from the French Database of PharmacoVigilance (FPVD) between 2002 and 2006. We investigated ADR related to TZD, focusing on 4 ADR: edema, heart failure, myocardial infarction and hepatitis corresponding to specific WHO-ART terms.

Results

Among a total of 99,284 adult patients in the FPVD, 2295 reports concerned type 2 diabetic patients (2.3% of the whole database), with 161 (7%) exposed to TZDs. The frequency of edema and cardiac failure was significantly higher with TZDs than in other patients (18% and 7.4% versus 0.8% and 0.1% respectively, p < 0.001) whereas the frequency of hepatitis was similar (5.9% versus 4%, NS). A multiple logistic regression model taking into account potential confounding factors (age, gender, drug exposure and co-morbidities) found that TZD exposure remained associated with heart failure and edema, but not with hepatitis or myocardial infarction.

Conclusions

Thiazolidinediones exposure is associated with an increased risk of edema and heart failure in patients with type 2 diabetes even when recommendations for use are respected. In contrast, the risk of hepatic reactions and myocardial infarction with this class of drugs seems to be similar to other hypoglycemic agents.

Diabetes mellitus and osteoporosis are two frequent multifactorial medical conditions with an increasing prevalence in the aging population. Patients with type 2 diabetes mellitus have an increased fracture risk despite a higher bone mineral density (BMD), which is mainly due to the increased risk of falls. Adequate glycemic control and prevention of diabetic complications are also the mainstay of therapy in type 2 diabetes mellitus. The thiazolidinediones (TZDs) have been demonstrated to improve insulin sensitivity and currently represent a widely prescribed treatment for type 2 diabetes. Their action is mediated by the binding to the nuclear receptor and transcription factor, peroxisome proliferator-activated receptor- γ (PPAR- γ), regulating the activity of other transcription factors in the adipogenic differentiation and inflammatory response pathways. The activation of PPAR- γ by TZDs may also cause an increase in bone marrow adiposity and a decrease in osteoblastogenesis, resulting in reduced bone formation. Clinical data are pointing out that the intake of thiazolidinediones by older patients with type 2 diabetes correlates with both the decrease of bone mineral density in the femoral neck and hip and a higher risk for fractures. Thus, health care providers, not only physicians, should carefully check the existence of risk factors for osteoporosis and factures in their patients before selecting them for thiazolidinediones treatment. Moreover, an adequate clinical follow-up of treated subjects is strongly recommended.

Evidence from rodent and in vitro models suggests that activation of PPAR-γ by thiazolidinediones (TZDs) causes increased bone marrow adiposity and decreased osteoblastogenesis, resulting in bone loss. TZDs are prescribed for the treatment of diabetes, providing an opportunity to determine whether PPAR-γ activation also impacts bone in humans. In addition, since type 2 diabetes is associated with higher fracture risk, an understanding of the clinical impact of TZDs on bone is needed to guide fracture prevention efforts in this population. This review summarizes current findings regarding type 2 diabetes and increased fracture risk and then considers the available evidence regarding TZD use and bone metabolism in humans.

Ian Douglas and colleagues analyze records from the UK General Practice Research Database, and find that among individuals prescribed thiazolidinediones who develop a fracture, fractures are more common during periods of thiazolidinedione exposure than unexposed periods.

Background

The results of clinical trials have suggested that the thiazolidinedione antidiabetic agents rosiglitazone and pioglitazone are associated with an increased risk of fractures, but such studies had limited power. The increased risk in these trials appeared to be limited to women and mainly involved fractures of the arm, wrist, hand, or foot: risk patterns that could not be readily explained. Our objective was to further investigate the risk of fracture associated with thiazolidinedione use.

Methods and Findings

The self-controlled case-series design was used to compare rates of fracture during thiazolidinedione exposed and unexposed periods and thus estimate within-person rate ratios. We used anonymised primary care data from the United Kingdom General Practice Research Database (GPRD). All patients aged 40 y or older with a recorded fracture and at least one prescription for a thiazolidinedione were included (n = 1,819). We found a within-person rate ratio of 1.43 (95% confidence interval [CI] 1.25–1.62) for fracture at any site comparing exposed with unexposed periods among patients prescribed any thiazolidinedione. This association was similar in men and women and in patients treated with either rosiglitazone or pioglitazone. The increased risk was also evident at a range of fracture sites, including hip, spine, arm, foot, wrist, or hand. The risk increased with increasing duration of thiazolidinedione exposure: rate ratio 2.00 (95% CI 1.48–2.70) for 4 y or more of exposure.

Conclusion

Within individuals who experience a fracture, fracture risk is increased during periods of exposure to thiazolidinediones (both rosiglitazone and pioglitazone) compared with unexposed periods. The increased risk is observed in both men and women and at a range of fracture sites. The risk also increases with longer duration of use.

Please see later in the article for the Editors' Summary

Editors' Summary

Background

Worldwide, nearly 250 million people have diabetes and this number is increasing rapidly, particularly in developing countries. Diabetes is a chronic disease characterized by dangerous amounts of sugar (glucose) in the blood. Blood-sugar levels are normally controlled by insulin, a hormone that the pancreas releases when blood-sugar levels rise after eating (the digestion of food produces glucose). Blood-sugar control fails in people with diabetes because they make no insulin (type 1 diabetes) or because the fat cells and muscle cells that usually respond to insulin by removing sugar from the blood have become insulin insensitive (type 2 diabetes). Type 1 diabetes is treated with insulin injections; type 2 diabetes—the most common type of diabetes—is controlled with diet, exercise, and antidiabetic pills, drugs that help the pancreas make more insulin (for example, sulfonylureas) or that make cells more sensitive to insulin (for example, thiazolidinediones). Long-term complications of diabetes include kidney failure, blindness, and nerve damage, and an increased risk of developing cardiovascular problems, including heart disease and strokes.

Why Was This Study Done?

Thiazolidinediones are widely used to treat type 2 diabetes but, worryingly, these drugs seem to increase people's risk of developing cardiovascular problems. In addition, they may increase the risk of bone fractures although the evidence for this particular association is limited. Given the large number of people with diabetes, it is important to understand the benefits and risks of thiazolidinedione treatment of diabetes as fully as possible. In this self-controlled case-series study, therefore, the researchers investigate the risk of fracture associated with the use of rosiglitazone and pioglitazone (two thiazolidinedione antidiabetic agents). A “self-controlled case-series study” compares how often an event (in this case, a fracture) occurs (the event's “rate”) in a population of individuals during a period of time when the individuals are not exposed to a medical intervention (in this case, treatment with thiazolidinediones) to its rate during a period when they are exposed to the intervention. Because each person acts as their own control, this study design helps to eliminate the possibility that unrecognized characteristics that vary between people (“confounders”) are responsible for differences in the event rate rather than the intervention itself.

What Did the Researchers Do and Find?

The researchers identified 1,819 people aged 40 years or older with a recorded fracture and at least one prescription for a thiazolidinedione by searching the UK General Practice Research Database, which contains personal and health data for more than 6 million UK residents. They compared these people's fracture rate during periods when they were taking a thiazolidinedione to their fracture rate when they weren't taking one of these drugs. After adjusting for age (age is a potential confounder because the risk of fractures increases with age and all the patients were older during their exposed period than during their unexposed period), the rate ratio for fracture at any site in patients during thiazolidinedione-exposed periods compared with thiazolidinedione-unexposed periods was 1.43. That is, nearly one and half times as many fractures occurred when people were taking thiazolidinediones than when they were not taking these drugs. The association between taking thiazolidinediones and the risk of fracture was similar in men and women and at several fracture sites but increased with the length of thiazolidinedione exposure.

What Do These Findings Mean?

These findings suggest that taking thiazolidinediones is associated with an increased risk of fracture at a wide range of sites in both men and women. They also suggest that the risk of fracture increases with treatment duration. These findings do not prove that thiazolidinediones cause fractures because, despite the self-controlled case-series design of this study, it remains possible that the people who have fractures share some unknown characteristic that affects their chances of breaking a bone. The accuracy of the findings is also dependent on the quality of the data in the General Practice Research Database. Nonetheless, these results are in keeping with the findings of clinical trials and other observational studies, suggesting they represent a real effect of treatment with thiazolidinediones. Although it is not clear yet how thiazolidinediones weaken bones, these findings need to be included in the ongoing debate about the risks and benefits of the treatment of type 2 diabetes with thiazolidinediones.

Additional Information

Please access these Web sites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.1000154.

The International Diabetes Federation provides information about all aspects of diabetes

The US National Diabetes Information ClearingHouse provides detailed information about diabetes (including information on medicines for diabetes) for patients, health-care professionals, and the general public (in English and Spanish)

The UK National Health Service also provides information for patients and carers about type 2 diabetes (in several languages)

MedlinePlus provides links to further resources and advice about diabetes and diabetes medicines (in English and Spanish)

Information about the UK General Practice Research Database and about the self-controlled case-series method is available

More information is available where the research was done at The London School of Hygiene & Tropical Medicine

TNF-alpha has been shown to be an important mediator of insulin resistance linked to obesity. This cytokine induces insulin resistance, at least in part, through inhibition of the tyrosine kinase activity of the insulin receptor. Recently, a new class of compounds, the antidiabetic thiazolidinediones (TZDs), has been shown to improve insulin resistance in obesity and non-insulin-dependent diabetes mellitus in both rodents and man. Here we show that TZDs have powerful effects on the ability of TNF-alpha to alter the most proximal steps of insulin signaling, including tyrosine phosphorylation of the insulin receptor and its major substrate, IRS-1, and activation of PI3-kinase. Troglitazone or pioglitazone essentially eliminate the reduction in tyrosine phosphorylation of IR and IRS-1 caused by TNF-alpha in fat cells, even at relatively high doses (25 ng/ml). That this effect of TZDs operates through activation of the nuclear receptor PPARgamma/ RXR complex is shown by the fact that similar effects are observed with other PPARgamma/RXR ligands such as 15 deoxy Delta12,14PGJ2 and LG268. The TZDs do not inhibit all TNF-alpha signaling in that the transcription factor NF-kB is still induced well. These data indicate that TZDs can specifically block certain actions of TNF-alpha related to insulin resistance, suggesting that this block may contribute to their antidiabetic actions.

OBJECTIVE

To review evidence supporting use of thiazolidinediones (TZDs) in management of type 2 diabetes mellitus (DM2).

QUALITY OF EVIDENCE

A MEDLINE search found several randomized controlled trials (level I evidence). No systematic reviews of these trials were found in the Cochrane Library.

MAIN MESSAGE

Thiazolidinediones lower hemoglobin AIc levels by as much as 1.0% to 1.5%. Effects can be seen in as little as 4 weeks, but full lowering takes 6 to 12 weeks. When used in combination with other diabetic agents, such as sulfonylureas and biguanides, TZDs’ hypoglycemic effects appear to be complementary. Thiazolidinediones directly improve insulin sensitivity and recovery of pancreatic beta cell function. Nevertheless, there is no evidence indicating that TZDs are superior to other antidiabetic agents currently available or that TZDs reduce the long-term complications of DM2.

CONCLUSION

Ongoing trials will further define the role of TZDs in management of diabetic patients. In current practice, cost is often a factor in the decision to prescribe TZDs.

Over the past two years, evidence has emerged that the currently available thiazolidinediones (TZDs), rosiglitazone, and pioglitazone have negative skeletal consequences, at least in women, which are clinically important. Increased fracture risk in women, but not men, was reported for both TZDs, based on analyses of adverse event reports from clinical trials. In short-term clinical trials in women, both TZDs caused more rapid bone loss. In these trials, changes in bone turnover markers suggest a pattern of reduced bone formation without a change in resorption. Although limited, these results support the hypothesis based on rodent and in vitro models that reduced bone formation resulting from activation of peroxisome proliferator-activated receptor-γ (PPARγ) is a central mechanism for TZDs' effect on bone. Research is needed to better understand the mechanisms of bone loss with TZDs, to identify factors that influence susceptibility to TZD-induced osteoporosis, and to test treatments for its prevention.

It is now well established that the development and progression of a variety of human malignancies are associated with dysregulated activity of the insulin-like growth factor (IGF) system. In this regard, promising drugs have been developed to target the IGF-I receptor or its ligands. These therapies are limited by the development of insulin resistance and compensatory hyperinsulinemia, which in turn, may stimulate cancer growth. Novel therapeutic approaches are, therefore, required. Synthetic PPAR-γ agonists, such as thiazolidinediones (TZDs), are drugs universally used as antidiabetic agents in patients with type 2 diabetes. In addition of acting as insulin sensitizers, PPAR-γ agonists mediate in vitro and in vivo pleiotropic anticancer effects. At least some of these effects appear to be linked with the downregulation of the IGF system, which is induced by the cross-talk of PPAR-γ agonists with multiple components of the IGF system signaling. As hyperinsulinemia is an emerging cancer risk factor, the insulin lowering action of PPAR-γ agonists may be expected to be also beneficial to reduce cancer development and/or progression. In light of these evidences, TZDs or other PPAR-γ agonists may be exploited in those tumors “addicted” to the IGF signaling and/or in tumors occurring in hyperinsulinemic patients.

A large number of cardiology clinical trials have mortality as an endpoint unless adequate surrogate endpoints are available. Although there are nine classes of agents used in the treatment of diabetes mellitus, none have shown a mortality benefit in clinical trials. The United Kingdom Prospective Diabetic Study was the first to suggest that metformin given for diabetes mellitus had a trend toward lowering mortality. The accidental discovery of peroxisome proliferator-activated receptors (PPARs) led to the introduction of the thiazolidinediones (TZD), a PPAR agent with a suggestion of a promise for the future. As the incidence of cardiovascular complications related to diabetes mellitus increases, there is a sense of urgency to produce antidiabetic medications that achieve not only nontoxic glycemic control but also improved cardiovascular outcomes. The goal of this review is to aid the clinician to appropriately assess the benefits and risks of TZD use when prescribing for patients.

Objective:

To derive a simple score for estimating the long-term risk of osteoporotic and hip fracture in individual patients with MS.

Methods:

Using the UK General Practice Research Database linked to the National Hospital Registry (1997–2008), we identified patients with incident MS (n = 5,494). They were matched 1:6 by year of birth, sex, and practice with patients without MS (control subjects). Cox proportional hazards models were used to calculate the long-term risk of osteoporotic and hip fracture. We fitted the regression model with general and specific risk factors, and the final Cox model was converted into integer risk scores.

Results:

In comparison with the FRAX calculator, our risk score contains several new risk factors that have been linked with fracture, which include MS, use of antidepressants, use of anticonvulsants, history of falling, and history of fatigue. We estimated the 5- and 10-year risks of osteoporotic and hip fracture in relation to the risk score. The C-statistic was moderate (0.67) for the prediction of osteoporotic fracture and excellent (0.89) for the prediction of hip fracture.

Conclusion:

This is the first clinical risk score for fracture risk estimation involving MS as a risk factor.

Aims

Thiazolidinediones (TZD) have been associated with an expansion in plasma volume and the development of peripheral oedema. A recent study reported an association between the use of TZDs and development of congestive heart failure (CHF). The objective of this study was to determine if short-term use of pioglitazone, a TZD, is associated with increased risk of CHF hospitalisation in a well-characterised, community-based cohort of type 2 diabetic patients without prevalent CHF.

Methods

A cohort study of all patients in the Kaiser Permanente Medical Care Program with type 2 diabetes (Kaiser Permanente Northern California Diabetes Registry) who initiated any diabetes pharmacotherapy (n=23,440) between October, 1999 and November, 2001. Only patients initiating single new therapies (“new users”) were included to reduce confounding and create mutually-exclusive exposure groups. We constructed Cox proportional hazards models (with sulfonylureas initiators specified as the reference group) to evaluate the impact of initiating new diabetes therapies on time to incident CHF hospitalisation, defined by primary hospital discharge diagnosis.

Results

Patients initiated pioglitazone (15.2%), sulfonylureas (25.3%), metformin (50.9%), and insulin (8.6%) alone or as additions to pre-existing or maintained therapies. Three hundred and twenty CHF hospitalisations were observed during the follow-up (10.2 months on average) after initiation. Relative to sulfonylurea initiators, there were no significant increases in the incidence of CHF hospitalisation among those initiating pioglitazone (hazard ratio (HR) = 1.28; 95% confidence interval (CI): 0.85 – 1.92) after adjusting for demographic, behavioural, and clinical factors. There was a significantly higher incidence among those initiating insulin (HR = 1.56; 95% CI: 1.00 – 2.45) and lower incidence among those initiating metformin, (HR = 0.70; 95% CI: 0.49 – 0.99).

Conclusions

This study of patients with type 2 diabetes failed to find evidence that short-term pioglitazone use was associated with an elevated risk of CHF hospitalisation relative to the standard, first line diabetes therapy.

Background/Aims: Thiazolidinediones (TZD) are a new class of oral antidiabetic drugs that have been shown to inhibit growth of some epithelial cancer cells. Although TZD were found to be ligands for peroxisome proliferators activated receptor γ (PPARγ) the mechanism by which TZD exert their anticancer effect is currently unclear. Furthermore, the effect of TZD on local motility and metastatic potential of cancer cells is unknown. The authors analysed the effects of two TZD, rosiglitazone and pioglitazone, on invasiveness of human pancreatic carcinoma cell lines in order to evaluate the potential therapeutic use of these drugs in pancreatic adenocarcinoma.

Methods: Expression of PPARγ in human pancreatic adenocarcinomas and pancreatic carcinoma cell lines was measured by reverse transcription polymerase chain reaction and confirmed by western blot analysis. PPARγ activity was evaluated by transient reporter gene assay. Invasion assay was performed in modified Boyden chambers. Gelatinolytic and fibrinolytic activity were evaluated by gel zymography.

Results: TZD inhibited pancreatic cancer cells’ invasiveness, affecting gelatinolytic and fibrinolytic activity with a mechanism independent of PPARγ activation and involving MMP-2 and PAI-1 expression.

Conclusion: TZD treatment in pancreatic cancer cells has potent inhibitory effects on growth and invasiveness suggesting that these drugs may have application for prevention and treatment of pancreatic cancer in humans.

Peroxisome proliferator-activated receptor γ (PPARγ) is a critical factor for adipogenesis and glucose metabolism, but accumulating evidence demonstrates the involvement of PPARγ in skeletal metabolism as well. PPARγ agonists, the thiazolidinediones (TZDs), have been widely used for the treatment of type 2 diabetes mellitus owing to their effectiveness in lowering blood glucose. However, the use of TZDs has been associated with bone loss and fractures. TZD-induced alterations in the bone marrow milieu—that is, increased marrow adiposity with suppression of osteogenesis—could partially explain the pathogenesis of TZD-induced bone loss Furthermore, several lines of evidence place PPARγ at the center of a regulatory loop between circadian networks and metabolic output. PPARγ exhibits a circadian expression pattern that is magnified by consumption of a high-fat diet. One of the circadian-regulated genes expressed in peripheral tissues, nocturnin (Noc), has been shown to enhance PPARγ activity. Importantly Noc-deficient mice are protected from diet-induced obesity, exhibit impaired circadian expression of PPARγ and have increased bone mass. This Review focuses on new findings regarding the role of PPARγ in adipose tissue and skeletal metabolism and summarizes the emerging role of PPARγ as an integral part of a complex circadian regulatory system that modulates food storage, energy consumption and skeletal metabolism.

Objective

The Peroxisome Proliferator Activated Receptor-gamma (PPARγ) protein is a nuclear transcriptional activator with importance in diabetes management as the molecular target for the thiazolidinedione (TZD) family of drugs. Substantial evidence indicates that the TZD family of PPARγ agonists may retard the development of atherosclerosis. However, recent clinical data has suggested that at least one TZD may increase the risk of myocardial infarction and death from cardiovascular disease. In this study, we used a genetic approach to disrupt PPARγ signaling to probe the protein's role in smooth muscle cell (SMC) responses that are important for atherosclerosis.

Results/Methods

SMC isolated from transgenic mice harboring the dominate-negative P465L mutation in PPARγ (PPARγL/+) exhibited greater proliferation and migration then did wild-type cells. Upregulation of ETS-1, but not ERK activation, correlated with enhanced proliferative and migratory responses PPARγL/+ SMCs. Following arterial injury, PPARγL/+ mice had a ~ 4.3-fold increase in the development of intimal hyperplasia.

Conclusion

These findings are consistent with a normal role for PPARγ in inhibiting SMC migration and proliferation in the context of restenosis or atherosclerosis.

There is uncertainty about the site(s) of action of the antidiabetic thiazolidinediones (TZDs). These drugs are agonist ligands of the transcription factor PPARγ, which is abundant in adipose tissue but is normally present at very low levels in liver and muscle. We have studied the effects of TZDs in A-ZIP/F-1 mice, which lack white adipose tissue. The A-ZIP/F-1 phenotype strikingly resembles that of humans with severe lipoatrophic diabetes, including the lack of fat, marked insulin resistance and hyperglycemia, hyperlipidemia, and fatty liver. Rosiglitazone or troglitazone treatment did not reduce glucose or insulin levels, suggesting that white adipose tissue is required for the antidiabetic effects of TZDs. However, TZD treatment was effective in lowering circulating triglycerides and increasing whole body fatty acid oxidation in the A-ZIP/F-1 mice, indicating that this effect occurs via targets other than white adipose tissue. A-ZIP/F-1 mice have markedly increased liver PPARγ mRNA levels, which may be a general property of fatty livers. Rosiglitazone treatment increased the triglyceride content of the steatotic livers of A-ZIP/F-1 and ob/ob mice, but not the “lean” livers of fat-transplanted A-ZIP/F-1 mice. In light of this evidence that rosiglitazone acts differently in steatotic livers, the effects of rosiglitazone, particularly on hepatic triglyceride levels, should be examined in humans with hepatic steatosis.

Background

Rosiglitazone and pioglitazone may increase the incidence of fractures. We aimed to determine systematically the risk of fractures associated with thiazolidinedione therapy and to evaluate the effect of the therapy on bone density.

Methods

We searched MEDLINE, EMBASE, the Cochrane Central Register of Controlled Trials (CENTRAL), other trial registries and product information sheets through June 2008. We selected long-term (≥ 1 year) randomized controlled trials involving patients with type 2 diabetes and controlled observational studies that described the risk of fractures or changes in bone density with thiazolidinediones. We calculated pooled odds ratios (ORs) for fractures and the weighted mean difference in bone density.

Results

We analyzed data from 10 randomized controlled trials involving 13 715 participants and from 2 observational studies involving 31 679 participants. Rosiglitazone and pioglitazone were associated with a significantly increased risk of fractures overall in the 10 randomized controlled trials (OR 1.45, 95% confidence interval [CI] 1.18–1.79; p < 0.001). Five randomized controlled trials showed a significantly increased risk of fractures among women (OR 2.23, 95% CI 1.65–3.01; p < 0.001) but not among men (OR 1.00, 95% CI 0.73–1.39; p = 0.98). The 2 observational studies demonstrated an increased risk of fractures associated with rosiglitazone and pioglitazone. Bone mineral density in women exposed to thiazolidinediones was significantly reduced at the lumbar spine (weighted mean difference –1.11%, 95% CI –2.08% to –0.14%; p = 0.02) and hip (weighted mean difference –1.24%, 95%CI –2.34% to –0.67%; p < 0.001) in 2 randomized controlled trials.

Interpretation

Long-term thiazolidinedione use doubles the risk of fractures among women with type 2 diabetes, without a significant increase in risk of fractures among men with type 2 diabetes.

Background

Osteoporosis is a debilitating condition characterized by fractures, pain and premature death. Risk factors for osteoporosis predict the risk of fragility fractures.

Aim

To describe the occurrence of risk factors for osteoporosis among populations in Nuuk, the capital of Greenland.

Methods

A random sample of women born in 1934–42, 1945–47, 1956, and men born in 1956 were selected from the national civil registry. A questionnaire was sent out in Greenlandic and Danish on risk factors for osteoporosis: family history, smoking habits, alcohol intake, presence of disease, sun exposure, intake of dairy products, age at menopause (women) and number of falls. Additional questions included the frequency of back pain, previous fractures, intake of vitamin D and calcium supplements, use of anti-osteoporotic drugs, steroids and other drugs.

Results

The questionnaire was sent to 317 subjects confirmed to be living at an address in Nuuk and 181 (57.1%) responded. More young women than older women were smokers (60.6% vs. 35.0%; p=0.022) while limited sun exposure was reported by more of the old women (37.2% vs. 5.6%; p=0.003). Family history of osteoporosis was reported by 15.0%, without difference between groups. Alcohol and milk intake did not differ between groups. Premature menopause was reported by 17.9% of the women. Falls within the last year were reported by 42.4% with fewer falls in the oldest age group (21.9% vs. 50.0%; p=0.005). Frequency of fragility fractures increased with age (5.7% vs. 24.3% vs. 30.4%; p=0.02) and the risk of a fragility fracture increased with age (p=0.004; OR, 95% CI: 4.5, 1.6–12.2, reference: below 70 years), when adjusted for smoking, gender and falls. The use of anti-osteoporotic drugs was low (3.4%) while 28.8% took calcium and vitamin D supplements.

Conclusions

Age is a dominating risk factor for fragility fractures in Greenland. The use of anti-osteoporotic drugs is low in Greenland, even if osteoporotic fractures are common in old age.