Blood sugar serum insulin and free fatty acid levels in normal dogs. Sex differences.

Sex influences on blood sugar, serum immunoreactive insulin and free fatty acid levels in normal dogs, basally and during intravenous glucose tolerance tests, were studied. Serum free fatty acid levels were the variable most affected by sex in our study. They were high in males in the post-absorptive condition, with a prompt, sharp suppressibility by combined hyperglycaemia and hyperinsulinaemia, followed by intense, subsequent rebound. Low in fasted females, they were poorly, non-significantly suppressed by glucose administration, and no subsequent rebound was observed. Insulin response was hardly impaired in males in respect to females, and neither blood sugar and serum insulin basal levels, nor the rate of glucose disappearance from blood depended upon sex.