Effects of Aging and Obesity on Insulin Secretion and Sensitivity

Kim, J Y; Jee, J H; Kim, H J; Lee, B W; Chung, Y J; Chung, J H; Min, Y K; Lee, M S; Lee, M K; Kim, K W

Abstract

BACKGROUND: Type 2 diabetes is occurring in epidemic proportions worldwide and aging has been defined as one of the risk factors for the progression to diabetes. The mechanism responsible for deterioration of glucose tolerance with aging is still unclear. It has been debated whether this deterioration results from an abnormal beta cell secretory function or/and decreased insulin sensitivity, from the aging process per se, or some other factors, such as an increase in BMI and abdominal fat. The changes in the insulin secretion and sensitivity were assessed in relation to aging and obesity, and the association between obesity and factors influencing glucose homeostasis in obese subjects evaluated.
METHODS
530 individuals, aged 24 to 75 years, having undergone a 75 g OGTT were enrolled, and the insulinogenic index and HOMA-IR calculated for each subject. 212 individuals were obese, i.e. a BMI above 25, which was evaluated from the body composition by CT at the umbilicus and thigh levels.
RESULTS
There was negative correlation between the insulinogenic index and age, but not between HOMA-IR and age. In relation to increasing age, the body composition changed toward a metabolically obese state, with increasing WHR, visceral fat area, VSR and VWR. Both the insulinogenic index and HOMA-IR were positively correlated with the anthropometric parameters.
CONCLUSION
The age-associated deterioration in glucose tolerance may be due to decreases in both insulin secretion and insulin sensitivity from changes in body composition