Prevalence of glucose intolerance in free‐ranging Macaca fascicularis of Mauritius

Oral glucose tolerance tests (OGTTs) were carried out on 30 free‐ranging long‐tailed macaques (Macaca fascicularis) on the island of Mauritius, following the suggestion that severe glucose intolerance and diabetes mellitus might be prevalent in this macaque population. OGTTs revealed no evidence of frank diabetes mellitus in the sample. However, 13% of individuals showed impaired glucose tolerance, with preserved insulin secretion, suggesting the presence of the target tissue resistance to insulin characteristic of human noninsulin‐dependent diabetes mellitus (NIDDM). The macaques with impaired glucose tolerance were neither obese nor aged. Glucose levels at all time points of the OGTT in normal macaques in our free‐ranging sample were lower than reported in captive populations, perhaps due to greater physical activity. Our observations demonstrate that a genetic predisposition to glucose intolerance does exist in M. fascicularis, and that this condition, well documented in laboratory macaques, is not simply an artifact of captivity.