Glucose metabolism was investigated in 21 patients with FA at the Instituto Neurogico, Cattedra di Clinica Medica, Milan, Italy. Abnormalities of glucose tolerance occurred in 5 (23.8%) and 4 were diabetic (19%). By oral glucose tolerance tests, the plasma glucose levels of 5 patients were 140-200 mg/ml 2 hours after glucose ingestion. Plasma insulin levels of glucose-intolerant patients were significantly higher than controls after 180 minutes following glucose ingestion. Plasma glucagon levels of FA patients were higher than controls, and plasma lactate levels of glucose intolerant FA patients were higher than controls. By intravenous glucose load, glucose responses did not differ significantly between patients and controls. The results showed that FA is associated with insulin resistance, B-cell deficiency, and type I diabetes. The alterations might be genetically linked or metabolically related to the primary defect in FA. 
COMMENT. Friedreich's ataxia, the most common heredodegenerative ataxia, is recessively inherited. The incidence of diabetes in FA patients is high, glucose intolerance during oral glucose tests have been reported previously, but the abnormalities of glucose metabolism have not previously been studied in detail. The abnormalities of glycemic control in FA may be due to the interplay of insulin resistance and B-cell dysfunction or their independent effects.