Effects of genetic severity on glucose homeostasis in Friedreich ataxia.

INTRODUCTION

Friedreich ataxia (FRDA) leads to increased risk of diabetes. Less is known regarding the dynamics of glucose homeostasis in FRDA, the influence of disease features, and the utility of oral-based metrics for capturing metabolic dysfunction.

METHODS

To examine these dynamics, we analyzed oral and intravenous glucose tolerance test data in 42 non-diabetic patients with FRDA.

RESULTS

Patients showed high insulin responsiveness to glucose and low insulin sensitivity. Genetic severity predicted overall metabolic impairment: individuals with longer guanine-adenine-adenine (GAA) repeats on the shorter allele showed a lower disposition index. Genetic severity did not predict any other variables. Measures of disposition index from intravenous and oral glucose tolerance testing did not correlate well, possibly reflecting divergent responses to oral and intravenous glucose loads.

CONCLUSIONS

FRDA patients demonstrate abnormal compensatory activity for managing glucose. Genetic severity impacts the global homeostatic profile, whereas relative contributions of insulin secretion and action vary from patient to patient. Muscle Nerve 54: 887-894, 2016.