Poor Glycemic Control Is Associated With Impaired Bone Accrual in the Year Following a Diagnosis of Type 1 Diabetes.

CONTEXT: Type 1 diabetes (T1D) is associated with an increased fracture risk across the life course. The effects on bone accrual early in the disease are unknown. OBJECTIVE: To characterize changes in bone density and structure over the year following diagnosis of T1D and to identify contributors to impaired bone accrual. DESIGN: Prospective cohort study. SETTING: Academic children's hospital. PARTICIPANTS: Thirty-six children, ages 7 to 17 years, enrolled at diagnosis of T1D. OUTCOMES: Whole body and regional dual-energy X-ray absorptiometry and tibia peripheral quantitative computed tomography obtained at baseline and 12 months. The primary outcome was bone accrual assessed by bone mineral content (BMC) and areal bone mineral density (aBMD) velocity z score. RESULTS: Participants had low total body less head (TBLH) BMC (z = -0.46 ± 0.76), femoral neck aBMD (z = -0.57 ± 0.99), and tibia cortical volumetric BMD (z = -0.44 ± 1.11) at diagnosis, compared with reference data, P < 0.05. TBLH BMC velocity in the year following diagnosis was lower in participants with poor (hemoglobin A1c ≥7.5%) vs good (hemoglobin A1c <7.5%) glycemic control at 12 months, z = -0.36 ± 0.84 vs 0.58 ± 0.71, P = 0.003. TBLH BMC velocity was correlated with gains in tibia cortical area (R = 0.71, P = 0.003) and periosteal circumference (R = 0.67, P = 0.007) z scores in participants with good, but not poor control. CONCLUSIONS: Our results suggest that the adverse effects of T1D on BMD develop early in the disease. Bone accrual following diagnosis was impaired in participants with poor glycemic control and appeared to be mediated by diminished bone formation on the periosteal surface.

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.

A0001 in Friedreich ataxia: biochemical characterization and effects in a clinical trial.

This study tested the ability of A0001 (α-tocopheryl quinone; EPI-A0001), a potent antioxidant, to improve in vitro measures, glucose metabolism, and neurological function in Friedreich ataxia. We used an in vitro study of protection from cell toxicity followed by a double-blind, randomized, placebo-controlled trial of 2 doses of A0001 in 31 adults with Friedreich ataxia. The primary clinical trial outcome was the Disposition Index, a measure of diabetic tendency, from a frequently sampled intravenous glucose tolerance test, evaluated 4 weeks into therapy. Secondary neurologic measures included the Friedreich Ataxia Rating Scale. A0001 potently inhibited cell death in Friedreich ataxia models in vitro. For the clinical trial, mean guanine-adenine-adenine repeat length was 699, and mean age was 31 years. Four weeks after treatment initiation, differences in changes in the Disposition Index between subjects treated with A0001 and placebo were not statistically significant. In contrast, a dose-dependent improvement in the Friedreich Ataxia Rating Scale score was observed. Patients on placebo improved 2.0 rating scale points, whereas patients on low-dose A0001 improved by 4.9 points (P = .04) and patients on a high dose improved by 6.1 points (P < .01). Although A0001 did not alter the Disposition Index, it caused a dose-dependent improvement in neurologic function, as measured by the Friedreich Ataxia Rating Scale. Longer studies will assess the reproducibility and persistence of neurologic benefit.