Diabetes Mellitus in Friedreich's Ataxia

In a clinical study of Friedreich's ataxia diabetes mellitus was found in nine of 50 typical cases. The mean age of the diabetes onset was 21.9 years and the clinical type was a severe ketosis-prone diabetes. In 18 non-diabetics an intravenous glucose tolerance test was performed. One of these cases was disclosed to be a prediabetes. The mean rate of glucose disappearance was normal. Serum lipid analysis showed a slight elevation in non-diabetics and a higher in diabetics. The frequency of diabetes mellitus, including the prediabetic case, was 20%. Owing to the low age of the cases and as the glucose tolerance test was performed only in about half of the non-diabetics, this figure was estimated to be lower than the total frequency in Friedreich's ataxia. A brief survey of the literature is given, and the aetiology of diabetes mellitus in Friedreich's ataxia is discussed. The marked frequency of a known heredity to diabetes in the diabetic cases lends support to the hypthesis of a genetic aetiology. The possibility of an interplay between the defective genes of the two diseases is assumed. The pronouncedly vegetative syndrome occurring in Friedreich's ataxia suggests the possibility of a central nervous factor, though this can hardly be a primary cause of the diabetes.