Abstract
A 12 year old girl with Friedreich's ataxia, in whom progression from chemical to severe insulin-dependent diabetes mellitus occurred over a two year period, is presented. During the phase of subclinical diabetes her plasma immunoreactive insulin response to oral glucose was markedly increased, but when she became symptomatic gross insulin deficiency had supervened. This report draws attention to the unusual disorders of carbohydrate metabolism and insulin secretion that may occur in a variety of neurological conditions.