The effects of low-dose intramuscular insulin therapy on endogenous glucagon secretion in diabetic ketoacidosis were compared prospectively with a conventional regimen. Ten patients, 4 to 15 years of age, who had 13 episodes of diabetic ketoacidosis, were alternately assigned to either group. Either 0.1 unit/kg regular insulin was given every two hours im, or 1.0 unit/kg regular insulin was given, half subcutaneously and half intravenously, every 4 hours. In both groups, a significant and equal fall in both serum glucose and glucagon concentrations was observed. No complications were encountered. It is concluded that 0.1 unit/kg of regular insulin given im every two hours is as effective in correcting hyperglycemia and hyperglucagonemia of diabetic ketoacidosis as is conventional therapy, and avoids the risks of secondary hypoglycemia known to occur when the larger insulin dosages are employed.