Euglycemia Indicates Favorable Motor Outcome in Parkinson's Disease

BACKGROUND: The interplay between glycemic control and Parkinson's disease (PD) has long been recognized but not fully understood. OBJECTIVES: To investigate the association of glycated hemoglobin (HbA1c) levels with motor and cognitive symptom progression in a prospective PD cohort. METHODS: Of 244 PD patients, 17 had low HbA1c (≤30 mmol/mol), 184 were euglycemic (HbA1c 31-41 mmol/mol), 18 had high HbA1c (HbA1 ≥42 mmol/mol), and 25 had diabetes mellitus (DM). Survival analysis was applied on time until Hoehn and Yahr stage ≥3 (motor outcome) and until mild cognitive impairment. RESULTS: Low HbA1c (HR 2.7; 95% CI 1.3-6; P = 0.01) as well as high HbA1c (HR 3.6; 95% CI 1.5-8.9; P = 0.005) but not DM were independent predictors of unfavorable motor outcome. CONCLUSIONS: Both high and low HbA1c levels may be associated with motor symptom progression in PD; however, further studies are needed to confirm these findings and increase understanding regarding causality.