A negative effect of poorly controlled diabetes mellitus on the treatment of Parkinson’s disease

Abstract

Objective: Converging evidence ranging from basic pathophysiology to epidemiological and clinical data has described a potential relationship between Parkinson’s disease (PD) and diabetes mellitus (DM). This study aimed to explore the effect of sugar control on the treatment of motor manifestations in PD. Methods: A total of 124 de novo PD patients were included in the study. The participants were classified into three groups, non-DM (n = 45), well-controlled (n = 41) and less-controlled DM (n = 38), based on the glycated hemoglobin (HbA1c) cut-off value of 7.0. Clinical parameters including Unified Parkinson’s Disease Rating Scale (UPDRS), Mini-Mental State Examination (MMSE), and Montreal Cognitive Assessment (MoCA) were evaluated serial twice apart from 1 year. Results: The less-controlled DM group revealed significantly lesser improvement in UPDRS III (baseline to follow-up, 38.1 ± 9.6 to 29.9 ± 7.8; p < 0.001) than those of either non-DM (36.6 ± 8.9 to 22.9 ± 5.7) and well-controlled group (37.0 ± 8.8 to 24.0 ± 6.0) after standard PD treatment for 1 year. A higher HbA1c was correlated with a lesser decline of UPDRS III (b, 0.47; p < 0.001) among PD with DM population. Less-controlled DM effectively predicted a lesser decline of UPDRS III (b = + 5.426; p < 0.001). Conclusions: Our results demonstrated a potential negative effect of sub-optimally controlled blood sugar on treating motor manifestations of PD. Careful glucose management might be a beneficial strategy to improve the burden of motor symptoms in PD who have coexisting DM.