Endothelial function deteriorates after glucose ingestion. This may be attributed to hyperglycemia-induced oxidative stress. Acute endurance exercise might improve postprandial endothelial function by enhancing glucoregulation and reducing postprandial hyperglycemia.
To determine if endurance exercise performed 17h prior to high-sugar food ingestion attenuates postprandial impairment in endothelial function.
Healthy men and women (n=13; age: 48±17y) were studied on 2 occasions: after ≥48h with no exercise (CON) and 17h after a 60-min bout of endurance exercise (EX). During each trial, brachial artery flow-mediated dilation (FMD) was used to assess endothelial function before and after the ingestion of a candy bar and soft drink. Glucose, insulin, and thiobarbiturate reactive substances (TBARS), as a marker of oxidative stress, were measured in blood obtained during each FMD measurement. Insulin sensitivity index (ISI) was calculated from the glucose and insulin data.
FMD decreased significantly after food ingestion in both trials. However, prior exercise shifted the entire FMD curve upward (main treatment effect: p=0.0002), resulting in a greater area under the curve for FMD (774±122 vs. 607±122 % · min, p=0.01). Prior exercise shifted the glucose and insulin curves downward (main treatment effects: p=0.05 and p=0.0007, respectively) and increased ISI (10.8±0.7 vs. 9.2±0.7, p=0.01). TBARS did not differ between trials.
Postprandial endothelial function was improved by endurance exercise performed ~17 hours earlier. This effect was accompanied by exercise-induced improvements in insulin action and reductions in glycemia but did not correspond with reductions in oxidative stress, as assessed by TBARS.
endothelial function; acute exercise; postprandial; hyperglycemia
The association of prediabetic states with endothelial dysfunction measured by flow‐mediated dilation (FMD) or endothelial biomarker levels remains controversial. We examined data from 5 ethnic groups to determine the association between glucose categories and FMD or endothelial biomarkers. We determined whether these associations vary by ethnic group or body mass index.
Methods and Results
We used data from 3516 participants from 5 race/ethnic groups with brachial FMD, endothelial biomarkers, and glucose category (normal, impaired fasting glucose [IFG], and diabetes) measures. There were significant ethnic differences in FMD, biomarker levels, and the prevalence of IFG and diabetes. However, all 5 ethnic groups showed similar patterns of higher FMD for the IFG group compared with the normal glucose and diabetes groups, which was most significant among whites and Asian Indians. Associations between glucose categories and endothelial biomarkers were more uniform, with the IFG and diabetes groups having higher biomarker levels than the normal glucose group. These associations did not change with further adjustment for fasting insulin levels. Whites with normal BMI had higher FMD values with higher glucose levels, but those with BMI in the overweight or obese categories had the inverse association (P for interaction=0.01).
The discordance of IFG being associated with higher FMD but more abnormal endothelial biomarker levels is a novel finding. This higher FMD for the IFG group was most notable in whites of normal BMI. The higher FMD among those with impaired fasting glucose may reflect differences in insulin signaling pathways between the endothelium and skeletal muscle.
biomarkers; diabetes; endothelium; ethnicity; insulin resistance
Recent studies indicate postprandial triglyceride (TG) had a better association with cardiovascular events and metabolic syndrome than fasting TG. The authors of the present study investigated the metabolic and clinical relevance of postprandial TG.
In a cross-sectional retrospective study, the authors of the present study compared fasting and postprandial TG and analyzed the relationship between postprandial TG and various demographic and metabolic parameters in 639 Korean subjects with type 2 diabetes (T2D, group I, n=539) and impaired fasting glucose (IFG, group II, n=100) after ingestion of a standardized liquid meal (total 500 kcal, 17.5 g fat, 68.5 g carbohydrate, and 17.5 g protein).
Fasting and postprandial TG were significantly correlated (r=0.973, r=0.937, P<0.001) in group I and II, respectively. Of the variables, total cholesterol, waist circumference and body mass index were significantly correlated with fasting and postprandial TG in both groups. Only postprandial TG showed a significant correlation with glucose metabolic parameters (e.g., postprandial glucose, homeostatic model assessment of insulin resistance [HOMA-IR], and fasting C-peptide) in subjects with T2D. Multiple regression analysis showed fasting TG and HOMA-IR could be predictable variables for postprandial TG in subjects with T2D.
Postprandial TG was very strongly correlated with fasting TG. The authors of the present study suggest insulin resistance may be more associated with postprandial TG than fasting TG in Korean T2D patients on a low-fat diet.
Diabetes; Diet, fat-restricted; Non-fasting triglyceride; Triglycerides
Background/aims. Postprandial hyperglycemia, an independent risk factor for cardiovascular disease, is accompanied by endothelial dysfunction. We studied the effect of oral glucose load on insulin and glucose fluctuations, and on postprandial endothelial function in healthy individuals in order to better understand and cope with the postprandial state in insulin resistant individuals. Methods. We assessed post-oral glucose load endothelial function (flow mediated dilation), plasma insulin, and blood glucose in 9 healthy subjects. Results. The largest increases in delta FMD values (fasting FMD value subtracted from postprandial FMD value) occurred at 3 hours after both glucose or placebo load, respectively: 4.80 ± 1.41 (P = .009) and 2.34 ± 1.47 (P = .15). Glucose and insulin
concentrations achieved maximum peaks at one hour post-glucose load. Conclusion. Oral glucose load does not induce endothelial dysfunction in healthy individuals with mean insulin and glucose values of 5.6 mmol/L and 27.2 mmol/L, respectively, 2 hours after glucose load.
Postprandial hyperglycemia is an early indicator of abnormality in glucose metabolism leading to type 2 diabetes. However, mechanisms that contribute to postprandial hyperglycemia have not been identified. This study showed that mice with targeted inactivation of the group 1B phospholipase A2 (Pla2g1b) gene displayed lower postprandial glycemia than that observed in wild-type mice after being fed a glucose-rich meal. The difference was caused by enhanced postprandial glucose uptake by the liver, heart, and muscle tissues as well as altered postprandial hepatic glucose metabolism in the Pla2g1b−/ − mice. These differences were attributed to a fivefold decrease in the amount of dietary phospholipids absorbed as lysophospholipids in Pla2g1b−/− mice compared with that observed in Pla2g1b+/+ mice. Elevating plasma lysophospholipid levels in Pla2g1b−/− mice via intraperitoneal injection resulted in glucose intolerance similar to that exhibited by Pla2g1b+/+mice. Studies with cultured hepatoma cells revealed that lysophospholipids dose-dependently suppressed insulin-stimulated glycogen synthesis. These results demonstrated that reduction of lysophospholipid absorption enhances insulin-mediated glucose metabolism and is protective against postprandial hyperglycemia.
Postprandial hyperlipidemia impairs endothelial function and participates in the development of atherosclerosis. We investigated the postprandial effects of a dipeptidyl peptidase IV inhibitor, alogliptin, on endothelial dysfunction and the lipid profile.
A randomized cross-over trial design in 10 healthy volunteers (8 males and 2 females, 35 ± 10 years) was performed. The postprandial effects before and after a 1-week treatment of 25 mg/day alogliptin on endothelial function were assessed with brachial artery flow-mediated dilation (FMD) and changing levels of lipids, apolipoprotein B48 (apoB-48), glucose, glucagon, insulin, and glucagon-like peptide-1 (GLP-1) during fasting and at 2, 4, 6, and 8 h after a standard meal loading test.
Alogliptin treatment significantly suppressed the postprandial elevation in serum triglyceride (incremental area under the curve [AUC]; 279 ± 31 vs. 182 ± 32 mg h/dl, p = 0.01), apoB-48 (incremental AUC; 15.4 ± 1.7 vs. 11.7 ± 1.1 μg h/ml, p = 0.04), and remnant lipoprotein cholesterol (RLP-C) (incremental AUC: 29.3 ± 3.2 vs. 17.6 ± 3.3 mg h/dl, p = 0.01). GLP-1 secretion was significantly increased after alogliptin treatment. Postprandial endothelial dysfunction (maximum decrease in%FMD, from −4.2 ± 0.5% to −2.6 ± 0.4%, p = 0.03) was significantly associated with the maximum change in apoB-48 (r = −0.46, p = 0.03) and RLP-C (r = −0.45, p = 0.04).
Alogliptin significantly improved postprandial endothelial dysfunction and postprandial lipemia, suggesting that alogliptin may be a promising anti-atherogenic agent.
Dipeptidyl peptidase IV inhibitor; Postprandial lipid; Triglyceride-rich lipoprotein; Endothelial dysfunction; Alogliptin
Patients with noninsulin-dependent diabetes mellitus (NIDDM) have both preprandial and postprandial hyperglycemia. To determine the mechanism responsible for the postprandial hyperglycemia, insulin secretion, insulin action, and the pattern of carbohydrate metabolism after glucose ingestion were assessed in patients with NIDDM and in matched nondiabetic subjects using the dual isotope and forearm catheterization techniques. Prior to meal ingestion, hepatic glucose release was increased (P less than 0.001) in the diabetic patients measured using [2-3H] or [3-3H] glucose. After meal ingestion, patients with NIDDM had excessive rates of systemic glucose entry (1,316 +/- 56 vs. 1,018 +/- 65 mg/kg X 7 h, P less than 0.01), primarily owing to a failure to suppress adequately endogenous glucose release (680 +/- 50 vs. 470 +/- 32 mg/kg X 7 h, P less than 0.01) from its high preprandial level. Despite impaired suppression of endogenous glucose production during a hyperinsulinemic glucose clamp (P less than 0.001) and decreased postprandial C-peptide response (P less than 0.05) in NIDDM, percent suppression of hepatic glucose release after oral glucose was comparable in the diabetic and nondiabetic subjects (45 +/- 3 vs. 39 +/- 2%). Although new glucose formation from meal-derived three-carbon precursors (53 +/- 3 vs. 40 +/- 7 mg/kg X 7 h, P less than 0.05) was greater in the diabetic patients, it accounted for only a minor part of this excessive postprandial hepatic glucose release. Postprandial hyperglycemia was exacerbated by the lack of an appropriate increase in glucose uptake whether measured isotopically or by forearm glucose uptake. Thus as has been proposed for fasting hyperglycemia, excessive hepatic glucose release and impaired glucose uptake are involved in the pathogenesis of postprandial hyperglycemia in patients with NIDDM.
Postprandial hyperglycemia is believed to affect vascular endothelial function. The aim of our study was to compare the effects of acarbose and nateglinide on postprandial endothelial dysfunction.
We recruited a total of 30 patients with newly diagnosed type 2 diabetes (19 men and 11 women, age 67.8 ± 7.3 years). Patients were randomly assigned to 3 groups receiving either 300 mg/day acarbose, 270 mg/day nateglinide, or no medication. A cookie test (consisting of 75 g carbohydrate, 25 g butter fat, and 7 g protein for a total of 553 kcal) was performed as dietary tolerance testing. During the cookie test, glucose and insulin levels were determined at 0, 30, 60, and 120 min after load. In addition, endothelial function was assessed by % flow-mediated dilation (FMD) of the brachial artery at 0 and 120 min after cookie load.
Postprandial glucose and insulin levels were similar in the 3 groups. Postprandial endothelial dysfunction was similar in the 3 groups before treatment. After 12 weeks of intervention, postprandial FMD was significantly improved in the acarbose group compared with the control group (6.8 ± 1.3% vs 5.2 ± 1.1%, p = 0.0022). Area under the curve (AUC) for insulin response was significantly increased in the nateglinide and control groups; however, no significant change was observed in the acarbose group.
Our results suggest that acarbose improves postprandial endothelial function by improvement of postprandial hyperglycemia, independent of postprandial hyperinsulinemia. Acarbose may thus have more beneficial effects on postprandial endothelial function in patients with type 2 diabetes than nateglinide.
The objective of this article was to develop a methodology to quantify the risk of suffering different grades of hypo- and hyperglycemia episodes in the postprandial state.
Interval predictions of patient postprandial glucose were performed during a 5-hour period after a meal for a set of 3315 scenarios. Uncertainty in the patient's insulin sensitivities and carbohydrate (CHO) contents of the planned meal was considered. A normalized area under the curve of the worst-case predicted glucose excursion for severe and mild hypo- and hyperglycemia glucose ranges was obtained and weighted accordingly to their importance. As a result, a comprehensive risk measure was obtained. A reference model of preprandial glucose values representing the behavior in different ranges was chosen by a ξ2 test. The relationship between the computed risk index and the probability of occurrence of events was analyzed for these reference models through 19,500 Monte Carlo simulations.
The obtained reference models for each preprandial glucose range were 100, 160, and 220 mg/dl. A relationship between the risk index ranges <10, 10–60, 60–120, and >120 and the probability of occurrence of mild and severe postprandial hyper- and hypoglycemia can be derived.
When intrapatient variability and uncertainty in the CHO content of the meal are considered, a safer prediction of possible hyper- and hypoglycemia episodes induced by the tested insulin therapy can be calculated.
blood glucose; glucose variability; interval analysis; simulation; type 1 diabetes mellitus
Background/Aims. Gestational diabetes mellitus (GDM) and milder gestational impaired glucose tolerance (GIGT) identify women who are at risk of developing cardiovascular disease. Endothelial dysfunction, as indicated by impaired flow-mediated dilatation (FMD) on brachial artery ultrasound, is an early marker of vascular disease. Thus, we sought to evaluate endothelial function in women with and without recent glucose intolerance in pregnancy. Methods. One-hundred and seventeen women underwent oral glucose tolerance testing (OGTT) in pregnancy, enabling stratification into those with normal gestational glucose tolerance (n = 59) and those with GDM or GIGT (n = 58). 6 years postpartum, they underwent a repeat of OGTT and brachial artery FMD studies, enabling assessment of FMD and 4 secondary vascular measures: FMD after 60 seconds (FMD60), baseline arterial diameter, peak shear rate, and reactive hyperemia. Results. There were no differences between the normal gestational glucose tolerance and GDM/GIGT groups in FMD (mean 8.5 versus 9.3%, P = 0.61), FMD60 (4.1 versus 5.1%, P = 0.33), baseline diameter (3.4 versus 3.4 mm, P = 0.66), peak shear rate (262.6 versus 274.8 s−1, P = 0.32), and reactive hyperemia (576.6 versus 496.7%, P = 0.07). After covariate adjustment, there were still no differences between the groups. Conclusion. Despite their long-term cardiovascular risk, women with glucose intolerance in pregnancy do not display endothelial dysfunction 6 years postpartum.
Although chronic effects of exercise on endothelial function are established, the impact of acute exercise on flow-mediated dilatation (FMD) of brachial artery has not been elucidated yet.
Eighty-six young healthy volunteers were prospectively enrolled from January 2011 to December 2011. The subjects completed FMD tests at rest and immediately after treadmill exercise test. Primary outcome was the impact of acute exercise on FMD, measured by the difference of FMD before and after exercise. Secondary outcomes were the relationship of gender and exercise habit with FMD.
Seventy-four subjects who met the eligibility criteria were included for analysis. Thirty-five (47.3%) were male, and the mean age was 22.7±2.7 years. FMD was reduced after exercise (8.98±4.69 to 7.51±4.03%; P=0.017) and the reduction was found in female group (10.36±5.26 to 7.62±3.71%; P=0.002) but not in male group. Post-exercise FMD was significantly impaired in subjects who did not exercise regularly (6.92±3.13% versus 8.95±5.33%; P=0.003). The decrease of FMD after exercise was greater in female group (−2.75±5.28% versus 0.27±3.24%; P=0.003) and was associated with exercise habit (β=2.532; P=0.027).
In healthy young subjects, FMD was reduced after a bout of acute exercise. The impact of acute exercise showed significant differences according to gender and exercise habit. FMD impairment after acute exercise was observed in females and subjects without regular exercise.
Flow-mediated dilatation; FMD; Acute exercise
Few studies have examined short term responses to the different contents of carbohydrate or fat in the meal, although long term effects of the high fat meal have been considered as compound risk factor for metabolic disorders. The aim of this study was to investigate the postprandial changes of plasma glucose, insulin and lipids upon intakes of high carbohydrate or high fat meal in young healthy women. Subjects were randomly assigned to either the high carbohydrate meal (HCM, 75% carbohydrate, n=13) or the high fat meal (HFM, 60% fat, n=12) groups. The meals were prepared as isocaloric typical Korean menu. Blood samples were obtained prior to and 30, 60, 90, 120, 180 and 240 minute after the meal. There were no significant differences on fasting blood parameters including glucose, insulin, lipids concentrations between the groups prior to the test. The HCM had higher blood glucose and insulin concentrations, reached the peak at 30 min and maintained for 240 min compared to the HFM (P<0.05). The HFM had higher plasma triglyceride (TG) and free fatty acid (FFA) concentrations, reached the peak at 120 min and maintained for 240 min compared to the HCM (P<0.05). It is concluded that macronutrients content in the meal may be an important determinant of postprandial substrate utilization in healthy women.
High carbohydrate meal; high fat meal; nutrient metabolism; insulin; kinetics
OBJECTIVE—Slowing of gastric emptying by hyperglycemia, a physiological response to minimize postprandial hyperglycemia, may be impaired in patients with type 1 diabetes. The causes and consequences on glucose homeostasis are unknown.
RESEARCH DESIGN AND METHODS—Consequences of euglycemia- and hyperglycemia-induced changes in gastric emptying on postprandial glucose fluxes and excursions were studied in 10 healthy subjects and 15 type 1 diabetic subjects after ingestion of a mixed meal using the double isotope approach ([6,6-2H2] and [1-13C]glucose) and scintigraphic measurements of gastric emptying.
RESULTS—Gastric emptying was greater in type 1 diabetic subjects (90–120 min, P < 0.03), and 50% retention times were comparable in healthy subjects and type 1 diabetic subjects (167 ± 8 vs. 152 ± 10, P = 0.32). Hyperglycemia markedly delayed gastric emptying in healthy subjects but did not alter it in type 1 diabetic subjects (50% retention time 222 ± 18 vs. 167 ± 8 min, P = 0.003 and 148 ± 9 vs. 152 ± 10 min, P = 0.51). Plasma islet amyloid polypeptide (IAPP) increased approximately fourfold in healthy subjects (P < 0.001), whereas it was undetectable in type 1 diabetic subjects. IAPP replacement, using the analog pramlintide, in type 1 diabetic subjects slowed gastric emptying to a comparable extent, as did hyperglycemia in healthy subjects (P < 0.14), and greatly reduced postprandial hyperglycemia (P < 00.1). Meal-derived glucose appearance in plasma (10.7 ± 0.5 vs. 6.8 ± 0.7 μmol · kg−1 · min−1, P < 0.001) was reduced, and splanchnic glucose sequestration increased (14.0 ± 3.0 vs. 25.0 ± 6.0%, P = 0.04).
CONCLUSIONS—In patients with type 1 diabetes the ability to delay gastric emptying in response to hyperglycemia is impaired. This impairment contributes to exaggerated rates of meal-derived glucose appearance and, ultimately, postprandial glucose excursions.
Postprandial hyperglycemia in insulin-deficient, insulin-dependent diabetic subjects may result from impaired suppression of endogenous glucose production and/or abnormal disposition of meal-derived glucose. To investigate the relative contributions of these processes and to determine whether 2 wk of near normoglycemia achieved by using intensive insulin therapy could restore the pattern of glucose disposal to normal, meal-related and endogenous rates of glucose appearance were measured isotopically after ingestion of a mixed meal that contained deuterated glucose in seven lean insulin-dependent and five lean nondiabetic subjects. Diabetic subjects were studied once when insulin deficient and again during intensive insulin therapy after 2 wk of near normoglycemia. Total glucose production was determined by using tritiated glucose and the contribution of meal-related glucose was determined by using the plasma enrichment of deuterated glucose. The elevated basal and peak postprandial plasma glucose concentrations (252 +/- 33 and 452 +/- 31 mg/dl) of diabetic subjects when insulin deficient were decreased by intensive insulin therapy to values (82 +/- 6 and 193 +/- 10 mg/dl, P less than 0.01) that approximated those of nondiabetic subjects (93 +/- 3 and 140 +/- 15 mg/dl, respectively). Total and endogenous rates of glucose appearance (3,091 +/- 523 and 1,814 +/- 474 mg/kg per 8 h) in the diabetic subjects were significantly (P less than 0.02) greater than those in non-diabetic subjects (1,718 +/- 34 and 620 +/- 98 mg/kg per 8 h, respectively), whereas meal-derived rates of glucose appearance did not differ. Intensive insulin therapy decreased (P less than 0.01) both total (1,581 +/- 98 mg/kg per 8 h) and endogenous (478 +/- 67 mg/kg per 8 h) glucose appearance to rates that approximated those observed in the nondiabetic subjects, but did not alter meal-related glucose appearance. Thus, excessive entry of glucose into the peripheral circulation in insulin-deficient diabetic patients after ingestion of a mixed meal resulted from a lack of appropriate suppression of endogenous glucose production rather than impairment of initial splanchnic glucose uptake. Intensive insulin therapy restored postprandial suppression of endogenous glucose production to rates observed in nondiabetic subjects.
In this study, we sought to determine whether postprandial insulin secretion, insulin action, glucose effectiveness, and glucose turnover were abnormal in type 2 diabetes.
RESEARCH DESIGN AND METHODS
Fourteen subjects with type 2 diabetes and 11 nondiabetic subjects matched for age, weight, and BMI underwent a mixed-meal test using the triple-tracer technique. Indexes of insulin secretion, insulin action, and glucose effectiveness were assessed using the oral “minimal” and C-peptide models.
Fasting and postprandial glucose concentrations were higher in the diabetic than nondiabetic subjects. Although peak insulin secretion was delayed (P < 0.001) and lower (P < 0.05) in type 2 diabetes, the integrated total postprandial insulin response did not differ between groups. Insulin action, insulin secretion, disposition indexes, and glucose effectiveness all were lower (P < 0.05) in diabetic than in nondiabetic subjects. Whereas the rate of meal glucose appearance did not differ between groups, the percent suppression of endogenous glucose production (EGP) was slightly delayed and the increment in glucose disappearance was substantially lower (P < 0.01) in diabetic subjects during the first 3 h after meal ingestion. Together, these defects resulted in an excessive rise in postprandial glucose concentrations in the diabetic subjects.
When measured using methods that avoid non–steady-state error, the rate of appearance of ingested glucose was normal and suppression of EGP was only minimally impaired. However, when considered in light of the prevailing glucose concentration, both were abnormal. In contrast, rates of postprandial glucose disappearance were substantially decreased due to defects in insulin secretion, insulin action, and glucose effectiveness.
Optimizing the hormonal environment during the postprandial period in favor of increased anabolism is of interest to many active individuals. Data are conflicting regarding the acute hormonal response to high fat and high carbohydrate feedings. Moreover, to our knowledge, no studies have compared the acute hormonal response to ingestion of lipid and carbohydrate meals of different size.
We compared the hormonal response to lipid and carbohydrate meals of different caloric content during the acute postprandial period. Nine healthy men (22 ± 2 years) consumed in a random order, cross-over design one of four meals/beverages during the morning hours in a rested and fasted state: dextrose at 75 g (300 kcals), dextrose at 150 g (600 kcals), lipid at 33 g (300 kcals), lipid at 66 g (600 kcals). Blood samples were collected Pre meal, and at 0.5 hr, 1 hr, 2 hr, and 3 hr post meal. Samples were assayed for testosterone, cortisol, and insulin using ELISA techniques. Area under the curve (AUC) was calculated for each variable, and a 4 × 5 ANOVA was used to further analyze data.
A meal × time effect (p = 0.0003) was noted for insulin, with values highest for the dextrose meals at the 0.5 hr and 1 hr times, and relatively unaffected by the lipid meals. No interaction (p = 0.98) or meal (p = 0.39) effect was noted for testosterone, nor was an interaction (p = 0.99) or meal (p = 0.65) effect noted for cortisol. However, a time effect was noted for both testosterone (p = 0.04) and cortisol (p < 0.0001), with values decreasing during the postprandial period. An AUC effect was noted for insulin (p = 0.001), with values higher for the dextrose meals compared to the lipid meals (p < 0.05). No AUC effect was noted for testosterone (p = 0.85) or cortisol (p = 0.84).
These data indicate that 1) little difference is noted in serum testosterone or cortisol during the acute postprandial period when healthy men consume lipid and dextrose meals of different size; 2) Both testosterone and cortisol experience a drop during the acute postprandial period, which is similar to what is expected based on the normal diurnal variation--feeding with lipid or dextrose meals does not appear to alter this pattern; 3) dextrose meals of either 75 g or 150 g result in a significant increase in serum insulin, in particular at 0.5 hr and 1 hr post-ingestion; 4) lipid meals have little impact on serum insulin.
Acute postprandial hyperglycemia is an important affector for atherosclerosis in subjects with glucose intolerance. We analyzed the relationship of brachial-ankle pulse wave velocity (baPWV) with fasting and post-challenge plasma glucose levels according to different time points during oral glucose tolerance test (OGTT).
In 663 subjects with fasting hyperglycemia, 75 g OGTT were performed to confirm the glucose tolerant status, and fasting, post-challenge 30-minute and 120-minute glucose levels were measured. Anthropometric measurements were done, and fasting lipid profiles were measured. baPWV were measured in all subjects and the relationship between fasting, 30- and 120-minute post-challenge glucose levels and baPWV were analyzed.
Among the participants, 62.9% were prediabetes and 31.7% were diabetes. Mean baPWV value was significantly higher in subjects with diabetes compared with prediabetes group. In bivariate correlation analyses, age, blood pressure, total cholesterol, low density lipoprotein cholesterol, 30-minute and 120-minute post-challenge glucose levels showed significant positive correlation with baPWV value. In multiple regression analysis, 30-minute post-challenge glucose level was a weak but significant determinant for mean baPWV value even after adjustment for other confounding variables.
Postprandial hyperglycemia, especially 30-minute glucose levels showed significant correlation with baPWV in subjects with fasting hyperglycemia. These results can imply the deleterious effect of acute hyperglycemic excursion on arterial stiffness in subjects with glucose intolerance.
Arterial stiffness; Oral glucose tolerance test; Postprandial hyperglycemia; Pulse wave analysis
Although earlier studies demonstrated endothelial dysfunction and systemic inflammation in patients with microvascular angina (MVA), the correlations between flow-mediated dilation (FMD), high-sensitivity C-reactive protein (hsCRP) levels and Duke treadmill score (DTS), a comprehensive index representing the severity of ischemia, have not been elucidated in this setting.
To explore the possible relationships among brachial FMD, serum hsCRP levels and DTS in MVA patients.
METHODS AND RESULTS:
A total of 89 subjects with chest pain and a normal coronary angiogram were studied. The exercise treadmill test (ETT) was performed using the Bruce protocol for calculating the DTS. Brachial FMD and serum hsCRP levels were measured. The mean (± SD) brachial FMD was 5.45±2.24% in the group with positive ETT and 8.19±2.78% in the group with a negative ETT (P<0.001). Mean serum hsCRP levels were significantly higher in the group with positive ETT than in the group with negative ETT (4.93±1.63 mg/L versus 3.41±1.65 mg/L; P<0.001). Brachial FMD and serum hsCRP levels showed significant differences among the three groups according to DTS risk stratification. The DTS was positively correlated with FMD (r=0.532; P<0.001) and negatively correlated with hsCRP level (r= 0.461; P<0.001).
Brachial FMD and serum hsCRP levels may be associated with DTS in patients with MVA.
Exercise treadmill test; Flow-mediated dilation; High-sensitivity C-reactive protein; Microvascular angina
Postprandial plasma nonesterified fatty acid (NEFA) appearance is increased in type 2 diabetes. Our objective was to determine whether skeletal muscle uptake of plasma NEFA is abnormal during the postprandial state in type 2 diabetes.
RESEARCH DESIGN AND METHODS
Thigh muscle blood flow and oxidative metabolism indexes and NEFA uptake were determined using positron emission tomography coupled with computed tomography (PET/CT) with [11C]acetate and 14(R,S)-[18F]fluoro-6-thia-heptadecanoic acid (18FTHA) in seven healthy control subjects (CON) and seven subjects with type 2 diabetes during continuous oral intake of a liquid meal to achieve steady postprandial NEFA levels with insulin infusion to maintain similar plasma glucose levels in both groups.
In the postprandial state, plasma NEFA level was higher in type 2 diabetic subjects versus CON (P < 0.01), whereas plasma glucose was at the same level in both groups. Muscle NEFA fractional extraction and blood flow index levels were 56% (P < 0.05) and 24% (P = 0.27) lower in type 2 diabetes, respectively. However, muscle NEFA uptake was similar to that of CON (quadriceps femoris [QF] 1.47 ± 0.23 vs. 1.37 ± 0.24 nmol ⋅ g−1 ⋅ min−1, P = 0.77; biceps femoris [BF] 1.54 ± 0.26 vs. 1.46 ± 0.28 nmol ⋅ g−1 ⋅ min−1, P = 0.85). Muscle oxidative metabolism was similar in both groups. Muscle NEFA fractional extraction and blood flow index were strongly and positively correlated (r = 0.79, P < 0.005).
Postprandial muscle NEFA uptake is normal despite elevated systemic NEFA levels and acute normalization of plasma glucose in type 2 diabetes. Lower postprandial muscle blood flow with resulting reduction in muscle NEFA fractional extraction may explain this phenomenon.
In glycemic control, postprandial glycemia may be important to monitor and optimize as it reveals glycemic control quality, and postprandial hyperglycemia partly predicts late diabetic complications. Self-monitoring of blood glucose (SMBG) may be an appropriate technology to use, but recommendations on measurement time are crucial.
We retrospectively analyzed interindividual and intraindividual variations in postprandial glycemic peak time. Continuous glucose monitoring (CGM) and carbohydrate intake were collected in 22 patients with type 1 diabetes mellitus. Meals were identified from carbohydrate intake data. For each meal, peak time was identified as time from meal to CGM zenith within 40–150 min after meal start. Interindividual (one-way Anova) and intraindividual (intraclass correlation coefficient) variation was calculated.
Nineteen patients were included with sufficient meal data quality. Mean peak time was 87 ± 29 min. Mean peak time differed significantly between patients (p = 0.02). Intraclass correlation coefficient was 0.29.
Significant interindividual and intraindividual variations exist in postprandial glycemia peak time, thus hindering simple and general advice regarding postprandial SMBG for detection of maximum values.
blood glucose self-monitoring; continuous glucose sensors; hyperglycemia; postprandial period; type 1 diabetes mellitus
Endothelium-derived nitric oxide (NO) mediates the arterial dilation following a flow increase (i.e. flow-mediated dilation, FMD), easily assessed in the brachial artery. NO is also involved in cerebral hemodynamics and it is supposed to trigger vascular changes occurring during migraine. This study aimed at investigating whether migraine patients present an altered response to NO also in the peripheral artery system.
We enrolled 21 migraineurs (10 with aura [MwA], 11 without aura [MwoA]), and 13 controls. FMD was evaluated with ultrasound in all subjects by measuring the percentage increase of the brachial artery diameter induced by hyperaemia reactive to sustained cuff inflation around the arm above systolic pressure. FMD values were then normalized for shear stress.
Normalized FMD values were higher in patients with MwA (28.5 10-2%.s) than in controls (9.0 10-2%.s) and patients with MwoA (13.7 10-2%.s) (p < 0.001). FMD was over the median value (19%) in 23.1% of controls, in 45.5% of the MwoA patients, and in 90% of the MwA patients.
Migraineurs with aura present an excessive arterial response to hyperaemia, likely as an effect of an increased sensitivity to endothelium-derived nitric oxide. This phenomenon observed peripherally might reflect similar characteristics in the cerebral circulation.
Endothelial dysfunction is frequently present in individuals with insulin resistance or type 2 diabetes and can be induced by high-fat or high-carbohydrate meals. Because exenatide reduces postprandial glucose and lipid excursions, we hypothesized that it may also improve postprandial endothelial function.
RESEARCH DESIGN AND METHODS
In a double-blinded randomized crossover design, postprandial endothelial function was examined in 28 individuals with impaired glucose tolerance or recent-onset type 2 diabetes after a single injection of exenatide or placebo given just before a high-fat meal. Endothelial function was determined with peripheral arterial tonometry pre- and postprandially.
Postprandial endothelial function was higher after exenatide compared with placebo (P = 0.0002). In the placebo phase, postprandial change in endothelial function was inversely associated with mean postprandial concentrations of triglycerides (r = −0.62, P = 0.0004). Changes in postprandial triglyceride concentrations explained 64% of exenatide's effect on postprandial endothelial function.
Exenatide ameliorates postprandial endothelial dysfunction after a high-fat meal.
Background. The magnitude and duration of postprandial blood glucose (PPG) elevations are important risk factors of diabetes and coronary heart diseases. Aim. To study PPG after ingestion of breads with and without pea fibre and rapeseed oil. Methods. After fasting overnight, 10 Pakistani immigrant women participated in three experiments having a crossover design and involving ingestion of various types of bread: regular coarse bread or fibre enriched-bread with two levels of rapeseed oil, all providing 25 g available carbohydrates (CHO). Blood glucose and satiety were determined before the meal and every 15 min over the next 2 hours. Results. Intake of an amount of pea fibre-enriched bread containing 25 g CHO attenuated, the postprandial peak glucose value, the incremental area under the glucose versus time curve during 15 to 75 min, and the glycemic profile, and increased duration of satiety (P < .05), as compared with intake of regular bread with 25 g carbohydrate. Conclusion. Pea fibre-enriched breads can reduce PPG and prolong satiety.
We examined the influences of obesity and diabetes on endothelium-dependent and -independent vasodilation, inflammatory cytokines, and growth factors. We included 258 subjects, age 21–80 years in four groups matched for age and gender: 40 healthy nonobese (BMI <30 kg·m−2) nondiabetic subjects, 76 nonobese diabetic patients, 37 obese (BMI >30) nondiabetic subjects, and 105 obese (BMI >30) diabetic patients. The flow-mediated dilation (FMD, endothelium-dependent) and nitroglycerin-induced dilation (NID, endothelium-independent) in the brachial artery, the vascular reactivity at the forearm skin and serum growth factors and inflammatory cytokines were measured. FMD was reduced in the nonobese diabetic patients, obese nondiabetic controls, and obese diabetic patients (P < 0.0001). NID was different among all four groups, being highest in the obese nondiabetic subjects and lowest in the obese diabetic patients (P < 0.0001). The resting skin forearm blood flow was reduced in the obese nondiabetic subjects (P < 0.01). Vascular endothelial growth factor (VEGF) was higher in the obese nondiabetic subjects (P < 0.05), tumor necrosis factor–α was higher in the obese diabetic patients (P < 0.0001) and C-reactive protein was higher in both the obese nondiabetic and diabetic subjects (P < 0.0001). Soluble intercellular adhesion molecule-1 was elevated in the two diabetic groups and the obese nondiabetic subjects (P < 0.05). We conclude that diabetes and obesity affect equally the endothelial cell function but the smooth muscle cell function is affected only by diabetes. In addition, the above findings may be related to differences that were observed in the growth factors and inflammatory cytokines.
Flow-mediated dilation (FMD) measures the ability of an artery to relax in response to increases in blood velocity. FMD, primarily of the brachial artery, has been used as a noninvasive method of assessing vascular health. The purpose of this study was to assess FMD in the lower legs of humans. Six healthy subjects (27 ± 6 yrs) were tested. Doppler ultrasound images of the posterior tibial artery were taken before, during, and after 5 minutes of proximal cuff occlusion. FMD was measured as the percent increase in diameter after cuff release. Vascular tone was calculated using the resting diameter as a percentage of the vessel's vasoactive range. Minimum diameter occurred during ischemia and maximal diameter occurred following reactive hyperemia with local heating. The lower leg was heated with 10 minutes of immersion in 44°C water. Mean diameters at rest, cuff, and during release were 0.267 ± 0.062, 0.162 ± 0.036, 0.302 ± 0.058 cm, respectively. FMD was 13.5 ± 6.6 % and vascular tone was 29 ± 16.3%. We also found that retesting on a second day produced mean diameter values within 8% of the first day. Larger resting diameter (decreased tone) correlated with decreased FMD (r2 = 0.73). These results suggest that FMD and vascular tone can be measured in the posterior tibial artery. This is a potentially powerful tool to non-invasively measure vascular health in the lower legs of people at risk for vascular disease.