Metabolic abnormalities among free-ranging Macaca mulatta on Cayo Santiago: Comparisons with Macaca mulatta at Sabana...

Free-ranging rhesus macaques (Macaca mulatta) were examined on the island of Cayo Santiago (CS), Puerto Rico, with intravenous glucose tolerance tests (IV-GTTs). Results were compared to monkeys derived from the island, but subsequently housed in corrals or gang cages at Sabana Seca (SS). Glucose clearance was similar among CS and SS macaques (range 2.99 to 4.50%min); both CS and SS males had significantly greater fasting serum glucose levels (63 ± 1 and 61 ± 2 mg/dl, respectively) than females; concentrations in CS and SS nonpregnant females (49 ± 3 vs. 52 ± 1 mg/dl) were significantly greater than CS and SS pregnant females (38 ± 3 vs. 41 ± 2 mg/dl) at each location. Fasting insulin was significantly less for male CS than for male SS macaques (means of 34 vs. 51 μU/ml); female averages were similar at both locations (range 48 to 61 μU/ml). The acute increment of insulin secretion for CS males was less than for SS males (85 vs. 136 μU/ml) but there were no differences between CS and SS females. The weight and body mass of CS macaques were generally greater than SS macaques. Hyperinsulinemic macaques > 10 years had greater weight and body mass compared to age-matched controls. Genetics may play a major role in expression of these impairments since the incidence on CS varied from 0 to 54% among the matrilines examined.