Cerebrospinal fluid sorbitol and myoinositol in diabetic polyneuropathy

Changes in cerebrospinal fluid (CSF) concentrations of sorbitol and myoinositol in 21 patients with diabetic polyneuropathy were studied with gas-liquid chromatography. The sorbitol concentration was significantly increased in diabetic patients with elevated plasma glucose. Myoinositol concentration was significantly decreased in patients with polyneuropathy compared with the controls. Both alterations in polyol concentrations of the CSF were present already two months from onset of symptoms of diabetes. Patients with peripheral polyneuropathy receiving oral hypoglycemic drugs did not have elevated plasma glucose and CSF sorbitol levels, but showed significantly decreased CSF myoinositol concentrations compared with the controls. These observations suggest that myoinositol concentration may be decreased in the central nervous system in adult onset mild diabetes with normal plasma glucose and that the decrease in the myoinositol in CSF possibly is connected with the development of neuropathy.