In June 2008, the Medical Advisory Secretariat began work on the Diabetes Strategy Evidence Project, an evidence-based review of the literature surrounding strategies for successful management and treatment of diabetes. This project came about when the Health System Strategy Division at the Ministry of Health and Long-Term Care subsequently asked the secretariat to provide an evidentiary platform for the Ministry’s newly released Diabetes Strategy.
After an initial review of the strategy and consultation with experts, the secretariat identified five key areas in which evidence was needed. Evidence-based analyses have been prepared for each of these five areas: insulin pumps, behavioural interventions, bariatric surgery, home telemonitoring, and community based care. For each area, an economic analysis was completed where appropriate and is described in a separate report.
To review these titles within the Diabetes Strategy Evidence series, please visit the Medical Advisory Secretariat Web site, http://www.health.gov.on.ca/english/providers/program/mas/mas_about.html,
- Diabetes Strategy Evidence Platform: Summary of Evidence-Based Analyses
- Continuous Subcutaneous Insulin Infusion Pumps for Type 1 and Type 2 Adult Diabetics: An Evidence-Based Analysis
- Behavioural Interventions for Type 2 Diabetes: An Evidence-Based Analysis
- Bariatric Surgery for People with Diabetes and Morbid Obesity: An Evidence-Based Summary
- Community-Based Care for the Management of Type 2 Diabetes: An Evidence-Based Analysis
- Home Telemonitoring for Type 2 Diabetes: An Evidence-Based Analysis
- Application of the Ontario Diabetes Economic Model (ODEM) to Determine the Cost-effectiveness and Budget Impact of Selected Type 2 Diabetes Interventions in Ontario
The objective of this report is to determine whether behavioural interventions1 are effective in improving glycemic control in adults with type 2 diabetes.
Diabetes is a serious chronic condition affecting millions of people worldwide and is the sixth leading cause of death in Canada. In 2005, an estimated 8.8% of Ontario’s population had diabetes, representing more than 816,000 Ontarians. The direct health care cost of diabetes was $1.76 billion in the year 2000 and is projected to rise to a total cost of $3.14 billion by 2016. Much of this cost arises from the serious long-term complications associated with the disease including: coronary heart disease, stroke, adult blindness, limb amputations and kidney disease.
Type 2 diabetes accounts for 90–95% of diabetes and while type 2 diabetes is more prevalent in people aged 40 years and older, prevalence in younger populations is increasing due to a rise in obesity and physical inactivity in children.
Data from the United Kingdom Prospective Diabetes Study (UKPDS) has shown that tight glycemic control can significantly reduce the risk of developing serious complications in type 2 diabetics. Despite physicians’ and patients’ knowledge of the importance of glycemic control, Canadian data has shown that only 38% of patients with diabetes have HbA1C levels in the optimal range of 7% or less. This statistic highlights the complexities involved in the management of diabetes, which is characterized by extensive patient involvement in addition to the support provided by physicians. An enormous demand is, therefore, placed on patients to self-manage the physical, emotional and psychological aspects of living with a chronic illness.
Despite differences in individual needs to cope with diabetes, there is general agreement for the necessity of supportive programs for patient self-management. While traditional programs were didactic models with the goal of improving patients’ knowledge of their disease, current models focus on behavioural approaches aimed at providing patients with the skills and strategies required to promote and change their behaviour.
Several meta-analyses and systematic reviews have demonstrated improved health outcomes with self-management support programs in type 2 diabetics. They have all, however, either looked at a specific component of self-management support programs (i.e. self-management education) or have been conducted in specific populations. Most reviews are also qualitative and do not clearly define the interventions of interest, making findings difficult to interpret. Moreover, heterogeneity in the interventions has led to conflicting evidence on the components of effective programs. There is thus much uncertainty regarding the optimal design and delivery of these programs by policymakers.
Evidence-Based Analysis of Effectiveness
- Are behavioural interventions effective in improving glycemic control in adults with type 2 diabetes?
- Is the effectiveness of the intervention impacted by intervention characteristics (e.g. delivery of intervention, length of intervention, mode of instruction, interventionist etc.)?
- English Language
- Published between January 1996 to August 2008
- Type 2 diabetic adult population (>18 years)
- Randomized controlled trials (RCTs)
- Systematic reviews, or meta-analyses
- Describing a multi-faceted self-management support intervention as defined by the 2007 Self-Management Mapping Guide (1)
- Reporting outcomes of glycemic control (HbA1c) with extractable data
- Studies with a minimum of 6-month follow up
- Studies with a control group other than usual care
- Studies with a sample size <30
- Studies without a clearly defined intervention
Outcomes of Interest
- Primary outcome: glycemic control (HbA1c)
- Secondary outcomes: systolic blood pressure (SBP) control, lipid control, change in smoking status, weight change, quality of life, knowledge, self-efficacy, managing psychosocial aspects of diabetes, assessing dissatisfaction and readiness to change, and setting and achieving diabetes goals.
A search was performed in OVID MEDLINE, MEDLINE In-Process and Other Non-Indexed Citations, EMBASE, the Cumulative Index to Nursing & Allied Health Literature (CINAHL), The Cochrane Library, and the International Agency for Health Technology Assessment (INAHTA) for studies published between January 1996 and August 2008. Abstracts were reviewed by a single author and studies meeting the inclusion criteria outlined above were obtained. Data on population characteristics, glycemic control outcomes, and study design were extracted. Reference lists were also checked for relevant studies. The quality of the evidence was assessed as being either high, moderate, low, or very low according to the GRADE methodology.
Summary of Findings
The search identified 638 citations published between 1996 and August 2008, of which 12 met the inclusion criteria and one was a meta-analysis (Gary et al. 2003). The remaining 11 studies were RCTs (9 were used in the meta-analysis) and only one was defined as small (total sample size N=47).
Summary of Participant Demographics across studies
A total of 2,549 participants were included in the 11 identified studies. The mean age of participants reported was approximately 58 years and the mean duration of diabetes was approximately 6 years. Most studies reported gender with a mean percentage of females of approximately 67%. Of the eleven studies, two focused only on women and four included only Hispanic individuals. All studies evaluated type 2 diabetes patients exclusively.
The studies were conducted between 2002 and 2008. Approximately six of 11 studies were carried out within the USA, with the remaining studies conducted in the UK, Sweden, and Israel (sample size ranged from 47 to 824 participants). The quality of the studies ranged from moderate to low with four of the studies being of moderate quality and the remaining seven of low quality (based on the Consort Checklist). Differences in quality were mainly due to methodological issues such as inadequate description of randomization, sample size calculation allocation concealment, blinding and uncertainty of the use of intention-to-treat (ITT) analysis. Patients were recruited from several settings: six studies from primary or general medical practices, three studies from the community (e.g. via advertisements), and two from outpatient diabetes clinics. A usual care control group was reported in nine of 11 of the studies and two studies reported some type of minimal diabetes care in addition to usual care for the control group.
All of the interventions examined in the studies were mapped to the 2007 Self-management Mapping Guide. The interventions most often focused on problem solving, goal setting and encouraging participants to engage in activities that protect and promote health (e.g. modifying behaviour, change in diet, and increase physical activity). All of the studies examined comprehensive interventions targeted at least two self-care topics (e.g. diet, physical activity, blood glucose monitoring, foot care, etc.). Despite the homogeneity in the aims of the interventions, there was substantial clinical heterogeneity in other intervention characteristics such as duration, intensity, setting, mode of delivery (group vs. individual), interventionist, and outcomes of interest (discussed below).
Duration, Intensity and Mode of Delivery
Intervention durations ranged from 2 days to 1 year, with many falling into the range of 6 to 10 weeks. The rest of the interventions fell into categories of ≤ 2 weeks (2 studies), 6 months (2 studies), or 1 year (3 studies). Intensity of the interventions varied widely from 6 hours over 2 days, to 52 hours over 1 year; however, the majority consisted of interventions of 6 to 15 hours. Both individual and group sessions were used to deliver interventions. Group counselling was used in five studies as a mode of instruction, three studies used both individual and group sessions, and one study used individual sessions as its sole mode of instruction. Three studies also incorporated the use of telephone support as part of the intervention.
Interventionists and Setting
The following interventionists were reported (highest to lowest percentage, categories not mutually exclusive): nurse (36%), dietician (18%), physician (9%), pharmacist (9%), peer leader/community worker (18%), and other (36%). The ‘other’ category included interventionists such as consultants and facilitators with unspecified professional backgrounds. The setting of most interventions was community-based (seven studies), followed by primary care practices (three studies). One study described an intervention conducted in a pharmacy setting.
Duration of follow up of the studies ranged from 6 months to 8 years with a median follow-up duration of 12 months. Nine studies followed up patients at a minimum of two time points. Despite clear reporting of outcomes at follow up time points, there was poor reporting on whether the follow up was measured from participant entry into study or from end of intervention. All studies reported measures of glycemic control, specifically HbA1c levels. BMI was measured in five studies, while body weight was reported in two studies. Cholesterol was examined in three studies and blood pressure reduction in two. Smoking status was only examined in one of the studies. Additional outcomes examined in the trials included patient satisfaction, quality of life, diabetes knowledge, diabetes medication reduction, and behaviour modification (i.e. daily consumption of fruits/vegetables, exercise etc). Meta-analysis of the studies identified a moderate but significant reduction in HbA1c levels -0.44% 95%CI: -0.60, -0.29) for behavioural interventions in comparison to usual care for adults with type 2 diabetes. Subgroup analyses suggested the largest effects in interventions which were of at least duration and interventions in diabetics with higher baseline HbA1c (≥9.0). The quality of the evidence according to GRADE for the overall estimate was moderate and the quality of evidence for the subgroup analyses was identified as low.
- Based on moderate quality evidence, behavioural interventions as defined by the 2007 Self-management mapping guide (Government of Victoria, Australia) produce a moderate reduction in HbA1c levels in patients with type 2 diabetes compared with usual care.
- Based on low quality evidence, the interventions with the largest effects are those:
- - in diabetics with higher baseline HbA1c (≥9.0)
- - in which the interventions were of at least 1 year in duration