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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). 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. [ABSTRACT FROM AUTHOR]

Rhesus macaques (Macaca mulatta) from Cayo Santiago were examined for evidence of carbohydrate intolerance indicative of potential development of non-insulin-dependent diabetes mellitus (NIDDM). Monkeys 6 to > 20 years from natal Groups J, M, and P, an AGED Group (all > 20 years), and unrelated monkeys removed from the island in association with other groups (CAYO), were examined with intravenous glucose tolerance tests (iv-GTT). Morphometric measurements were made on all tested monkeys. Impairments included fasting hyperglycemia (> 115 mg/dl), impaired glucose clearance (K <2.0%/min), fasting hyperinsulinemia (> 150 μ/ml) or hypoinsulinemia (< 20 μU/ml), and insulin secretory abnormalities (> 500 μ/ml or < 75 μ/ml). Natal groups J and M had 31% with impairments, group P had 0% the AGED group had 45%, and the CAYO group had 33%. Impaired glucose clearance was usually attributable to a reduced insulin response. Impairments correlated significantly (p ≤ 0.05) to body weight and a modified Quetelet index, but not to sex, acute stress, or islet cell antibodies; the relationships to age could not be delineated in this survey. Impairments in monkeys are indicative of various stages in the asynchronous development of carbohydrate intolerance leading to NIDDM. [ABSTRACT FROM AUTHOR]

Spontaneous obesity in free-ranging rhesus macaques (Macaca mulatta) was assessed in terms of body size, body fat distribution, endocrinological/metabolic indices, and social and familial factors. Eleven animals (six females, five males), or 7% of the adult population surveyed, were defined as obese on the basis of morphometric indices of adiposity > 2 s.d. above the mean for adults in this colony. The age of the obese animals ranged from 9-16 years; obese males were older than females (average 14 vs. 12 years), but this difference was not significant. Mean body weights for obese males and females were 14.1 +/- 0.5 and 13.5 +/- 0.7 kg, respectively. There were no gender differences in either the incidence of obesity or measures of body fat. Serum concentrations of cholesterol and testosterone were not significantly different between obese and nonobese monkeys. Serum triglyceride levels were somewhat higher in obese animals, but this difference was not significant. Glucose clearance was within normal limits in both obese and age- and sex-matched non-obese monkeys (> 2% per min). Although increased adiposity was significantly correlated with fasting insulin and the insulin response to glucose loading, differences between obese and non-obese animals in these values did not achieve significance. The incidence of obesity ranged from 0-20% among the eleven matrilines studied, and several primary familial relationships were observed within the obese sample. Most obese females were from a high ranking matriline whereas only one of the obese males was high ranking at the time of the survey.(ABSTRACT TRUNCATED AT 250 WORDS)

Macaca mulatta on Cayo Santiago (CS) were examined with intravenous glucose tolerance tests (IV-GTT) for evidence of abnormalities in glucose clearance and insulin secretion. About 10% of the 98 monkeys had impaired glucose clearance associated with impaired insulin secretion. Another 6% had either fasting or secretory hyperinsulinemia with slightly increased rates of glucose clearance, and 20% had low insulin secretion, but no significant changes in glucose clearance. Results were compared to those obtained with CS-derived monkeys tested at Sabana Seca (SS). Glucose clearance per amount of insulin secreted was 40% more effective among CS macaques than among those at SS. There were no differences in weight between impaired and control macaques on CS. Effects of genetics, physical activity, and food consumption can be studied among these macaques and results related to similar metabolic abnormalities in prediabetic and diabetic human beings.