Diabetes mellitus among the Navajo. II. Plasma glucose and insulin responses.

Plasma glucose and insulin concentrations were determined in Navajo diabetic and control groups following the oral administration of 100 gm of glucose. On the basis of the maximal rise in plasma glucose, the diabetic patients could be classified into two groups: those with severe (group 1) and mild (group 2) carbohydrate intolerance. The Navajo control group had a brisk rise in plasma insulin to a mean peak concentration of 141.2 micro-units/ml. The plasma insulin response of the diabetic patients with mild glucose intolerance (group 2) was indistinguishable from that of the control group. Those diabetics with marked glucose intolerance (group 1), however, had a small and delayed rise in plasma insulin concentration. Thus markedly diminished carbohydrate intolerance in the Navajo appears to be secondary to a state of insulinopenia.