A Case of Idiopathic Diabetes Insipidus Complicated by Diabetes Mellitus

A 53-year-old female was admitted in November 1987 for polyuria (up to 5 liters daily) and polydipsia. Her blood glucose levels, however, were within the normal range. In June 1989 she lost her appetite and drank almost 10 liters of a cooling beverage. She was readmitted in July 1989 because of nausea and vomiting. Her urine volume was 8 to 10 liters/day, her blood glucose level was 624 mg/dl, and HbA1C 15.9%. The patient was severely dehydrated. The fluid and electrolyte deficit was replaced, she was treated with insulin infusion, and her blood glucose level normalized. Two months later the patient's urine C-peptide level had gradually improved, and a glucose tolerance test showed impaired glucose tolerance. Insulin administration was discontinued after six weeks, and the patient's diabetes mellitus was under good control on diet therapy. Polyuria and polydipsia nevertheless persisted, and a diagnosis of central diabetes insipidus was made on the basis of a water restriction test. After nasal inhalation of DDAVP (1-deamino-8-arginine vasopressin), the polyuria and polydipsia were ameliorated. The glucose intolerance and excess of glucose intake resulted in hyperglycemia, and we suppose that the transient failure of insulin secretion which caused severe hyperglycemia was attributable to stress and severe dehydration due to the osmotic diuresis and water diuresis of diabetes insipidus.