Occurrence of Diabetes Mellitus in Obese Nondiabetic Patients, with Correlative Analysis of Visceral Fat, Fasting Insulin, and Insulin Resistance: A 3-year Follow-up Study (Mysore Visceral Adiposity in Diabetes Follow-up Study)

OBJECTIVE: To assess the occurrence of diabetes in obese nondiabetic patients over a 3-year follow-up period with a correlative analysis of visceral fat (VF), fasting insulin levels, (FILs) and insulin resistance (IR). MATERIAL AND METHODS: Thirty-seven obese and nineteen nonobese nondiabetics of our previous study, Mysore Visceral Adiposity in Diabetes were followed for the next 3 years. Their blood pressure, body mass index, waist circumference (WC), fasting blood sugar (FBS), FIL, lipid profile and subcutaneous fat (SCF), and VF measurement by US method were repeated every 6 months for the next 3 years. The findings were analyzed with appropriate statistical methods. RESULTS: Twenty-three obese and 18 nonobese nondiabetics completed the study. There were 17 dropouts. The changes in the physical and biochemical characteristics of the two groups before and after the study were not significant. SCF had no correlation with IR whereas VF correlated with FIL and IR. There were three diabetics in the obese group and two from the control group at the end of the study. There were 12 impaired glucose tolerance (IGT) in the test group and 2 in the control group. Those who developed diabetes had higher VF, WC, FBS, FIL, and IR. Those who showed IGT also had these at higher levels compared to others. There was no change in the VF at the end of the study. CONCLUSIONS: This follow-up study on South Indians has shown that VF is a significant risk factor for the development of IR. IR can develop without any increase in the volume of the VF, is the essential finding of this study. SCF has not shown any significant relationship with IR. We recommend FBS and FIL in all the obese nondiabetics to calculate IR, which has given much insight in the development of IGT and diabetes. Large multicentric, longitudinal studies are required to establish the cause of IR.