DIET RESTRICTION IN RHESUS-MONKEYS LOWERS FASTING AND GLUCOSE-STIMULATED GLUCOREGULATORY END-POINTS

Male rhesus monkeys (Macaca mulatta) of different age groups represent ing the species life span were fed ad libitum or a 30% reduced calorie diet over a 7-yr period. During the first 2-3 yr of this longitudinal study, glucose and insulin levels were not altered by diet restrictio n (DR). However, reductions in fasting blood glucose became apparent i n DR animals after 3-4 yr. At the end of the 6th yr of study, glycated hemoglobin was measured, and intravenous glucose tolerance tests (IVG TTs) were conducted. Maximum glucose levels reached during IVGTTs incr eased with age but were lower in DR animals compared with controls. Se veral measures of the insulin response (baseline, maximum, and integra ted areas under curve) increased with age and were lower in DR monkeys . With the exception of glycated hemoglobin, which was not different i n monkeys subjected to DR, these findings confirm previous studies in rodents demonstrating that DR alters glucose metabolism and may be rel ated to the antiaging action of this intervention.