The Diabetes Prevention Program: baseline characteristics of the randomized cohort. The Diabetes Prevention Program Research Group

Projected impact of implementing the results of the diabetes prevention program in the U.S. population

OBJECTIVE

To determine the feasibility of using either fasting plasma glucose or HbA(1c) to identify individuals in the U.S. population who meet the Diabetes Prevention Program (DPP) criteria for intervention, defined as BMI >/=24 kg/m(2), fasting plasma glucose level 96-125 mg/dl, and 2-h glucose level 140-199 mg/dl in an oral glucose tolerance test (OGTT).

RESEARCH DESIGN AND METHODS

Analysis of a representative sample of U.S. adults aged 40-74 years with no medical history of diabetes for whom data on height, weight, fasting plasma glucose, HbA(1c), and 2-h plasma glucose during an OGTT were obtained. Sensitivity, specificity, positive predictive value (PPV), and receiver operator characteristic (ROC) curves for fasting glucose and HbA(1c) were determined.

RESULTS

Using BMI <24 kg/m(2) as an initial criterion eliminated 27.2% of U.S. adults from further testing. Of the remaining group, 41.1% did not have to be considered for an OGTT because their fasting glucose level was below or above 96-125 mg/dl. Overall, 10.6% of adults aged 40-74 years without medical history of diabetes met the DPP eligibility criteria for intervention. Among individuals with BMI >/=24 kg/m(2) and fasting glucose level 96-125 mg/dl, applying a fasting plasma glucose cutoff of >/=105 mg/dl excluded 62.5% of this group and resulted in 56.0% of those with 2-h glucose level 140-199 mg/dl in this group being identified, with a specificity of 72.0% and a PPV of 17.1%. Similar values were obtained for an HbA(1c) cutoff value of >/=5.5%.

CONCLUSIONS

Using data on BMI and setting cutoff values for fasting glucose and HbA(1c) would greatly reduce the number of individuals who would need to undergo an OGTT while achieving adequate sensitivity, specificity, and PPV.

Psychological and behavioral correlates of baseline BMI in the diabetes prevention program (DPP)

OBJECTIVE

To determine psychological and behavioral correlates of baseline BMI in the Diabetes Prevention Program (DPP).

RESEARCH DESIGN AND METHODS

Of 1,079 DPP lifestyle intervention participants, 274 completed validated questionnaires at baseline assessing weight loss history, stage of change, self-efficacy, dietary restraint, emotional eating, binge eating, perceived stress, depression, and anxiety.

RESULTS

The mean age of subjects was 52.5 years, 65% were women, and their mean BMI was 33.9 kg/m(2). Higher BMI correlated with more frequent weight cycling (r = 0.50, P < 0.0001) and efforts at weight loss (r = 0.34, P < 0.0001); younger age when first overweight (r = -0.42, P < 0.0001); lower exercise efficacy (r = -0.15, P = 0.015); lower weight loss efficacy (r = -0.21, P < 0.001); a less advanced stage of change for weight loss (r = -0.12, P = 0.04); more perceived stress (r = 0.14, P = 0.02); emotional eating (r = 0.19, P = 0.001); poor dietary restraint (r = -0.14, P = 0.02); binge eating frequency (r = 0.18, P = 0.004) and severity (r = 0.30, P < 0.0001); feeling deprived, angry, or upset while dieting (r = 0.27, P </= 0.0001); and food cravings while dieting (r = 0.31, P < 0.0001). Correlations did not differ as a function of sex; however, correlations of BMI with anxiety and low-fat diet and weight loss self-efficacy differed as a function of ethnicity. In multivariate models, binge eating severity, poor dietary restraint, and food craving were independent correlates of baseline BMI.

CONCLUSIONS

Many psychological and behavioral factors are associated with higher BMI in this ethnically diverse group of men and women. Whether strategies that help patients increase levels of dietary restraint and reduce binge eating and food craving lead to long-term weight loss maintenance needs longitudinal study.

Orlistat in the treatment of Type 2 diabetes mellitus

The prevalence of Type 2 diabetes mellitus (DM-2) is increasing throughout the world and poses a major public health concern. With the majority of patients DM-2 are overweight or obese and weight loss is generally recommended, both as a first-line therapy and as an adjunct to pharmacological therapies. However, it is generally acknowledged that weight loss, a difficult goal for many overweight and obese individuals, is especially difficult for those with DM-2 and there is interest in whether pharmacological adjuncts may be useful for this purpose. Orlistat is an intestinal lipase inhibitor previously approved for the treatment of obesity. During the past several years, clinical trials have been completed concerning the use of orlistat in the treatment of overweight or obese patients with DM-2. The purpose of this review is to examine the results of these clinical trials. Data on > 2500 orlistat-treated patients with DM-2 are reviewed and summarised. Orlistat therapy led to greater weight loss and improved metabolic control in overweight and obese patients with DM-2.

The Diabetes Prevention Program: recruitment methods and results

The Diabetes Prevention Program (DPP) is a multicenter randomized controlled trial designed to test whether diet and exercise or medication can prevent or delay the onset of type 2 diabetes in persons with impaired glucose tolerance, who are at increased risk of the disease. This paper describes DPP recruitment methods, strategies, performance, and costs. The DPP developed an organizational structure for comprehensive management and continuous monitoring of recruitment efforts. The DPP utilized a variety of recruitment strategies, alone or in combination, and a stepped informed consent procedure leading to randomization. Studywide and clinic-specific recruitment data were monitored, analyzed, and used to modify recruitment approaches. DPP recruitment was completed slightly ahead of schedule, meeting goals for the proportion of women enrolled and nearly meeting goals for the proportion of racial/ethnic minorities. Clinics varied widely in the recruitment strategies they used, and these strategies also varied by participant age, gender, and race/ethnicity. Staff time devoted to recruitment averaged 86.8 hours per week per clinic, with the majority of effort by staff specifically assigned to recruitment. The number of staff hours required to recruit a participant varied by recruitment strategy. Recruitment cost (excluding staff cost) was about 1075 US dollars per randomized participant. The DPP experience offers lessons for those planning similar efforts: (1) a method for ongoing assessment and revision of recruitment strategies is valuable; (2) a range of recruitment strategies may be useful; (3) the most effective methods for recruiting potential subjects may vary according to the gender, age, and race/ethnicity of those individuals; (4) recruitment strategies vary in the amount of staff time required to randomize a participant; and (5) a stepped screening may make it easier to identify and recruit volunteers who understand the requirements of the study.

[Significant incidence of type 2 diabetes on high-risk Spanish population. The IGT Study (2)]

BACKGROUND

Our purpose was to estimate the incidence of type 2 diabetes among a high risk population with or without impaired glucose tolerance (IGT), analysing the progression to diabetes.

PATIENTS AND METHOD

Multicenter cohort study on high risk individuals without diabetes (WHO-85 criteria) in primary health care. Subjects underwent an oral glucose tolerance test measuring fasting plasma glucose (FPG) and plasma glucose at 2 hours (2hPG). Mean follow-up was 37.2 months (4.3-69.7). Phenotypic features, diagnostic variation, diabetes incidence and predictive factors (multivariate analysis and Cox proportional hazards model) were assessed.

RESULTS

We included 243 individuals (148 females), aged 59.7 (10) years, with FPG < 7.8 mM and 2hPG < 11.1 mM. 137 IGT subjects (56.4%) and 106 (43.6%) normal glucose tolerance (NGT) subjects with a similar risk factor impact were evaluated. After the study was closed, 63 (25.9%) subjects developed diabetes: 43 (31.4%) with baseline IGT and 20 (18.9%) with NGT. Overall diabetes incidence increased over time but not proportionally. Mean annual incidence was 9.2% and it dropped to 4.6% when FPG was used as the unique diagnosis criterion (ADA-97). Male under 65 years with both overweight and IGT reported the highest incidence. HbA1c, FPG and 2hPG were independent predictors. Increased HDL cholesterol showed a protective effect on diabetes incidence. The IGT diagnosis interval was a much better predictor [OR = 2.06 (1.56-2.72)] of diabetes development than the impaired FPG diagnosis interval [OR = 1.37 (0.93-2.04)].

CONCLUSIONS

FPG predicted but undervalued diabetes incidence in high risk population. The IGT (2hPG) diagnosis interval predicted diabetes development better than the impaired fasting plasma glucose diagnosis interval. Increased diabetes incidence in high risk Spanish population, particularly with regard to IGT, means that primary preventive resources should be increased.

Reduction in the incidence of type 2 diabetes with lifestyle intervention or metformin

BACKGROUND

Type 2 diabetes affects approximately 8 percent of adults in the United States. Some risk factors--elevated plasma glucose concentrations in the fasting state and after an oral glucose load, overweight, and a sedentary lifestyle--are potentially reversible. We hypothesized that modifying these factors with a lifestyle-intervention program or the administration of metformin would prevent or delay the development of diabetes.

METHODS

We randomly assigned 3234 nondiabetic persons with elevated fasting and post-load plasma glucose concentrations to placebo, metformin (850 mg twice daily), or a lifestyle-modification program with the goals of at least a 7 percent weight loss and at least 150 minutes of physical activity per week. The mean age of the participants was 51 years, and the mean body-mass index (the weight in kilograms divided by the square of the height in meters) was 34.0; 68 percent were women, and 45 percent were members of minority groups.

RESULTS

The average follow-up was 2.8 years. The incidence of diabetes was 11.0, 7.8, and 4.8 cases per 100 person-years in the placebo, metformin, and lifestyle groups, respectively. The lifestyle intervention reduced the incidence by 58 percent (95 percent confidence interval, 48 to 66 percent) and metformin by 31 percent (95 percent confidence interval, 17 to 43 percent), as compared with placebo; the lifestyle intervention was significantly more effective than metformin. To prevent one case of diabetes during a period of three years, 6.9 persons would have to participate in the lifestyle-intervention program, and 13.9 would have to receive metformin.

CONCLUSIONS

Lifestyle changes and treatment with metformin both reduced the incidence of diabetes in persons at high risk. The lifestyle intervention was more effective than metformin.

Obesity and sedentary lifestyle: modifiable risk factors for prevention of type 2 diabetes

Over the past 25 years, the prevalence and incidence of type 2 diabetes have increased alarmingly worldwide and across all age, gender, and race/ethnic groups. The high economic costs, resulting from the numerous and severe complications of this disease, as well as the social burden associated with diabetes mellitus, have motivated the pursuit of prevention methods. Recently, clinical and observational studies have demonstrated the adverse effects of obesity and sedentary lifestyle, as well as the benefits of moderate weight loss and related behaviors, including increased levels of physical activity, in maintaining metabolic control and reducing the incidence of type 2 diabetes. The challenge remains to find ways to successfully deliver this message to the communities, and to evaluate the cost-effectiveness of the different delivery approaches.