A Case of Type 1 Diabetes Mellitus With Intractable Chronic Diarrhea and Challenging Glycemic Control.

The first step in treating diabetes mellitus (DM)-related diarrhea is to thoroughly control the serum glucose level. The authors herein describe a 75-year-old man who was diagnosed with type 1 DM when he was 32 years old. The patient lost his appetite due to hot weather and spent a week eating sweets and drinking juice. As a result, he developed diabetic ketoacidosis and was initially treated in another hospital, and then transferred to our facility for glycemic control two weeks later. He had been suffering from watery diarrhea for more than 100 days after being admitted to our hospital. His blood glucose control was extremely difficult, fluctuating between 30 and 500 mg/dL while watery diarrhea continued, and microscopic colitis was diagnosed by histological examination through endoscopy. Despite the use of insulin, multiple antidiarrheal agents including salazosulfapyridine, and a switch to total parenteral nutrition, his blood glucose fluctuations did not improve. In addition, his liver function deteriorated, his renal function declined, and hypoproteinemia developed. Considering drug-induced liver dysfunction, steroids were administered despite the high risk of further poor glycemic control. Following steroid administration, his liver function rapidly improved and the watery diarrhea resolved within a few days. Contrary to our concerns, his blood glucose level stabilized between 100 and 200 mg/dL. The mechanism underlying the stabilization of blood glucose levels after steroid use remains unclear. Prior to steroid administration, the frequency of diarrhea had been reduced from more than five times a day to only once or twice a day with antidiarrheal agents; nevertheless, the patient's glycemic control worsened. Therefore, the stabilization of his blood glucose cannot simply be attributed to the resolution of the diarrhea. This case suggests that steroid administration may be a consideration in patients with DM-related watery diarrhea who show a poor response to antidiarrheal agents and severe blood glucose fluctuations.