Table 2

Predictors of diabetes risk reduction through lifestyle intervention

StudyRelevant findings
Da Qing IGT and Diabetes Study (5,2729,81)• Diet, exercise, and a combination of diet and exercise intervention for 6 years in Chinese adults with IGT were equally effective in reducing diabetes incidence.
• Interventions were effective in people with a BMI higher or lower than 25 kg/m2.
• Benefit could not be wholly ascribed to changes in BMI.
• Interventions were most effective in those with less insulin resistance and greater insulin secretion at baseline.
• Reduced cumulative diabetes incidence persisted for at least 17 years after the termination of the active intervention.
• Lifestyle intervention was associated with a subsequent lower incidence of severe retinopathy and lower mortality.
Finnish Diabetes Prevention Study (DPS) (8289)• Lifestyle intervention was most effective among the oldest participants and those scoring highest on a composite risk assessment at baseline. This scoring instrument or others like it may be useful for identifying individuals most likely to benefit from intensive lifestyle intervention.
• Participants who had greater insulin sensitivity and better insulin secretion during the study were less likely to progress to diabetes during a mean follow-up of 6 years. Regression to NGT was more strongly associated with greater insulin secretion than with better insulin sensitivity.
• Participants with greater improvements in weight and BMI during the first year were less likely to develop diabetes. Thus, BMI reduction may be a key goal to improve insulin sensitivity, preserve insulin secretion, and ultimately prevent or delay diabetes.
• Achievement of each of the study’s five lifestyle goals significantly decreased risk. None of the participants who achieved at least four of the five goals developed diabetes by year 4.
• Participants with longer typical sleep durations had a higher risk of developing diabetes in the control group but not in the intervention group; lifestyle intervention was similarly effective regardless of participants’ sleep habits. Thus, lifestyle intervention may reduce the excess risk conferred by longer sleep duration.
• Several genetic variants conferred higher diabetes risk. Post hoc analyses showed that although lifestyle intervention was effective regardless of family history of diabetes its effectiveness varied markedly according to participants’ genetic variant status. This demonstrates the potential role of genotype in diabetes prevention efforts.
Diabetes Prevention Program (DPP) (7,34,35,9094)• Short- and long-term effects of intensive lifestyle intervention were greatest among older participants, those with greater baseline insulin sensitivity and insulin secretion, and those with greater improvements in each during the active study period.
• For women with a history of GDM, lifestyle modification and metformin were similarly effective, whereas for women without previous GDM, only lifestyle intervention reduced diabetes risk.
• Lifestyle intervention was similarly effective in those with and without higher genetic risk.
• The presence or absence of diabetes-related antibodies did not affect diabetes risk or predict responses to intervention.
• Individuals from any group who regained NGT at least once during active intervention reduced their diabetes risk by 56% during long-term follow-up compared with those with persistent prediabetes. Thus, even transient reversion to NGT by any means appears to lower future diabetes risk. Reversion was more common in the lifestyle group and was more likely in participants who achieved greater weight loss, were younger, and had lower glucose levels and better β-cell function at baseline. Paradoxically, lifestyle group members who did not revert to NGT during the study were actually at higher risk during follow-up, perhaps because of a particularly strong susceptibility (genetic or environmental) to diabetes. Thus, a combination of interventions may be needed for individuals whose dysglycemia is not reversed through lifestyle modification alone.
Indian Diabetes Prevention Programme-1 (IDPP-1) (95)• Baseline A1C was the most significant predictor of diabetes; however, preventive interventions were similarly effective across A1C subgroups.
• Lifestyle intervention reduced diabetes risk in this population independent of weight loss.
Indian text-messaging intervention study (76,96,97)• Participants who regained NGT by 6 months reduced their risk of progression to diabetes by 75% by year 2 compared with those who did not return to NGT within the first 6 months. Better β-cell function at baseline and its improvement during the study were associated with reversion to NGT by 2 years.
• Progression to diabetes was associated with declining β-cell function throughout the study period.
Zensharen Study for Prevention of Lifestyle Diseases (11)• Lifestyle intervention was highly effective in participants with combined IGT and IFG and in those with a baseline A1C ≥5.6% (Japan Diabetes Society method).
• Lifestyle intervention was ineffective in participants with isolated IFG and in those with a baseline A1C <5.6%.
Japanese study on prevention of type 2 diabetes by lifestyle intervention (12)• The cumulative 4-year incidence of diabetes, based on confirmed diagnostic FPG levels of 140 mg/dL (7.8 mmol/L) or higher, was 3.0% in the intensive and 9.3% in the conventional group.
• Changes in BMI only partially accounted for the lower incidence in the intensive group.