Treatment of diabetes insipidus complicated by diabetes mellitus with chlorpropamide and clofibrate.

A patient with severe idiopathic diabetes insipidus, complicated by diabetes mellitus, was first treated with a combination o clofibrate and chlorpropamide. Urine volume dropped from 18 litres/day (CH2O = 10.5 ml/min) to 3.1-5.1 litres/day (CH2O = -0.1 -+1.1 ml/min) under treatment. Ten months after the beginning of therapy treatment was maintained with chlorpropamide alone; no significant rise in urine volume was observed. After 18 months when therapy was stopped for 5 days urine volume rose to 11.7 litres/day maximum (CH2O = 6.6 ml/min). No obvious side effects occurred under treatment during a follow up for over 18 months. Serum levels for arginine vasopressin before and under treatment were below 1.0 pg/ml. Determination of free water clearance (CH2O) proved to be a highly sensitive and simple method for follow up controls. It is discussed whether the coincidental manifestation of diabetes insipidus and diabetes mellitus may be caused by a single molecular lesion. This hypothesis is supported by data which imply that in both disease chlorpropamide acts via a common molecular mechanism, the blocking of endogenous prostaglandin E2 biosynthesis. Finally a treatment with oral "non-hormonal" drugs like clofibrate and chlorpropamide should be taken into consideration in some cases of diabetes insipidus as is demonstrated by this case report.