Twenty-four consecutively admitted episodes of acute diabetic dysregulation in 22 patients were treated with a low-dose insulin regimen, given as hourly i.m. injections of 5 IU insulin. The fall in blood glucose was almost linear during the first 8 hours of treatment, on an average 10 percent per hour of the initial value. The hyperglycemia and acidosis were corrected by 2-12 hours of treatment. The deficiency of water and electrolytes, especially potassium, was treated with infusion from the beginnning, and the fluid balance was corrected within 12-16 hours. A severe fall in plasma potassium was never seen, but hypokalemia (less than 3.6mEg/I) was still present in some cases after 24 hours of treatment. One patient died on account of a large myocardial infarction, but otherwise the patients were restored to habitual condition in 1-4 days. The regimen was found to be simple, safe and effective in all cases, without risk of late hypoglycemia or severe hypokalemia. The study indicates, however, that the parenteral supply of potassium advocated previously, 12.5 mEq/hour, is not sufficient when the plasma potassium on admission is below 5.0mEq/I. In such cases it is recommended that the rate of potassium infusion is increased.