A 19-year-old woman with insulin-dependent diabetes mellitus (IDDM) of 3.5 years duration had been suffering from recurrent episodes of diabetic ketoacidosis (DKA), dizziness, and weight loss (16 kg, 29%) for 6 months. History and physical examination gave evidence of severe peripheral and autonomic neuropathy. Radionuclide retention on gastric emptying test at 60 min was greater than 90% (normal < 60%). On autonomic cardiovascular testing there was evidence of both parasympathetic and sympathetic damage. There was no evidence of nephropathy or retinopathy. Optimal diabetic control using 4 insulin injections (2 u/kg/day) and high-dose cisapride terminated the vomiting, and she regained the weight lost within 5 months. This case is unique in that severe diabetic neuropathy followed relatively soon after onset of disease, without other microvascular complications. The correct diagnosis of gastroparesis as the cause of the recurrent DKA and weight loss, and the specific prokinetic therapy and nearly normoglycemic control of the diabetes led to dramatic clinical and functional improvement. Specific prokinetic therapy and the nearly normoglycemic control of the diabetes led to dramatic clinical and functional improvement. Gastroparesis can cause recurrent DKA even in young patients with IDDM of short duration.