Abstract
A 52-year-old man with a 9-year history of diabetes mellitus was admitted to our hospital because of dysesthesia in his extremities, orthostatic dizziness and marked emaciation (body mass index 13.4). On admission a casual blood glucose was 494 mg/dl and HbA1c 14.9%. Although his blood glucose level had been improving in response to insulin treatment (14-18 U/day), hyponatremia (109 mEq/l) and hypoosmolarity (236 mOsm/l) developed 2 months after admission. Subsequent water restriction restored these abnormalities to normal levels, and further examination failed to show any renal or endocrinological disorders, or malignant lesions, central nervous system or respiratory disorders. These findings led us to a diagnosis of SIADH. A water loading test showed a negative free water clearance and the plasma ADH response was not suppressed. These findings had partially normalized 8 months after admission when diabetic neuropathy became alleviated together with weight gain. These results suggest that a diabetic autonomic neuropathy could induce SIADH via osmoreceptor dysfunction.
