Abstract

Objective: Indian Diabetes Prevention Programme-1(IDPP-1), showed that life style modification(LSM) and metformin were effective for primary prevention of diabetes in subjects with impaired glucose tolerance(IGT). Among subjects followed up for 3 years (n=502), risk reduction versus control group was 28.5%, 26.4% and 28.2% in LSM, metformin and LSM+metformin groups. In this analysis, role of changes, in secretion and action of insulin in improving the outcome were studied.

Research design and methods: For this analysis, 437 subjects (Normoglycaemia(NGT)=93, IGT=150, Diabetes=194) were included. Measurements of anthropometry, plasma glucose and plasma insulin at baseline and at follow up were available for all of them. Indices of insulin resistance (IR,HOMA-IR) and β-cell function,(insulinogenic index (‡ I/G);(30 min-fasting insulin÷30min glucose))were also analysed in relation to the outcome.

Results: Subjects with IGT showed a deterioration in β-cell function with time. Persons with higher IR and/or low β-cell function at baseline had poor outcome on follow up. In relation to no abnormalities, highest incidence of diabetes occurred when both abnormalities coexisted (54.9% vs 33.7%, χ²=7.53, p=0.006). Persons having abnormal IR (41.1%) or abnormal ‡ I/G (51.2%, χ²=4.87,p=0.027 vs no abnormalities) had lower incidence. Normal β-cell function with improved insulin sensitivity facilitated reversal to NGT whereas a deterioration in both resulted in diabetes. The beneficial changes were better with intervention than in the control group. Intervention groups had higher rates of NGT and lower rates of diabetes.

Conclusions: In the IDPP-1 subjects, beneficial outcomes occurred due to improved insulin action and sensitivity, caused by the intervention strategies.