Impaired glucose tolerance and heterogeneity of insulin responses in cows with abomasal displacement.

Injections of glucagon in dairy cows resulted in a rapid and marked increase in serum insulin and also in plasma glucose. Glucagon injection appears to be a simple and useful method for testing insulin secretion and glucose release. There was a somewhat reduced insulin response 2 weeks after calving in normal cows. Cows given high intensity feeding before calving showed higher plasma glucose levels in the glucagon test 3 days post partum and showed signs of reduced sensitivity to insulin action. Cows with abomasal displacement showed impaired glucose tolerance and heterogeneity of insulin responses indicating insulin resistance and signs of Type 2 (non-insulin-dependent) diabetes mellitus.