Long-term dietary restriction in older-aged rhesus monkeys: effects on insulin resistance

Long-term dietary restriction to maintain constant body weight in adult rhesus monkeys prevents the development of impaired glucose tolerance, hyperglycemia, and noninsulin-dependent diabetes mellitus. We sought to determine whether these positive antidiabetogenic effects of reduced calorie intake with maintenance of normal lean body weight might be mediated through prevention of the development of insulin resistance. Insulin-stimulated glucose uptake was assessed by the euglycemic hyperinsulinemic clamp technique in seven older-aged rhesus monkeys (20.7 +/- 0.6 years) who had been dietary restricted for 9 +/- 2 years. Results were compared to seven ad libitum-fed nondiabetic monkeys of similar age (21.0 +/- 1.3 years). Results showed that the dietary restricted monkeys had significantly higher in vivo insulin action compared to the ad libitum-fed group (14.06 +/- 2.4 vs 7.75 +/- 0.9 mg/kg FFM/min, respectively; p < .03). We conclude that long-term dietary restriction is an effective means of mitigating the development of significant insulin resistance in older-aged rhesus monkeys, and may be the mechanism underlying the prevention of Type II diabetes in this model.