Abnormal insulin secretion in amyotrophic lateral sclerosis

Plasma glucose and insulin (IRI) values during a 50-g oral glucose tolerance test were measured in patients with amyotrophic lateral sclerosis (ALS). Blood sugar curves were abnormal in 7 out of 18 patients in whom glucose tolerance tests were performed, and mean values of plasma glucose levels at 30, 60 and 120 min after glucose loading in the patients were significantly higher than those in control subjects. All cases with generalized muscle atrophy showed abnormal glucose tolerance except for 2 cases who showed borderline response, while in cases with localized atrophy, all but one borderline case demonstrated normal response. IRI response in patients with ALS was abnormal in 11 out of 14 cases, and the mean value at 30 min after glucose administration in the patients was significantly lower than that in control subjects; it was abnormal even in patients who did not have generalized muscle atrophy and showed normal glucose tolerance. The results suggest that abnormal glucose metabolism in ALS is primarily based on the impairment of pancreatic insulin secretion and that the addition of generalized muscle atrophy to the above factor results in apparently abnormal glucose utilization.