A Preliminary Study on whether HbA 1c Levels can Predict Visual Dependence for Spatial Orientation in Asymptomatic Type 2 Diabetic Patients

Introduction : Diabetes-induced vestibular dysfunction has been commonly reported, and asymptomatic patients with type 2 diabetes display higher degrees of perceptual visual dependence for spatial orientation than healthy controls. This study aims to assess whether HbA 1c can predict such visual dependence in the diabetic patients. Methods and Materials : Diabetic patients were divided into 2 groups: 22 subjects with “good” (HbA 1c 1c ≥ 7%) glycemic control. Otolithic vestibular function was tested using the computerized rod-and-frame test (CRFT) and results for the two diabetic groups were compared to 29 healthy controls. Results : When the frame was tilted, the diabetic group with “good” glycemic control had largest positioning errors, with a significant difference only in comparison to the control group. The “good” glycemic group exhibited larger degree of asymmetry under titled frame condition. Although HbA 1c was not associated with vestibular asymmetry in any diabetic group, it was significantly associated with visual dependence in the “good” glycemic group. During frame tilts, 10 diabetic patients had positioning errors above the reference range of 3.3°, 8 of which belonged to the “good” glycemic diabetic group. Conclusions : Diabetes disease processes may affect vestibular symmetry during visuo-vestibular conflicts, even in asymptomatic diabetics within the recommended glycemic range. The weak correlations between HbA 1c and CRFT parameters may indicate that HbA 1c cannot fully predict visual dependence or asymmetry on the CRFT in patients with diabetes, and different glycemic disorders may affect vestibular dependent spatial orientation in diabetic patients.