Dementia is associated with insulin resistance in patients with Parkinson's disease

Background: Parkinson's disease is a neurodegenerative disorder involving the basal ganglia. Type-2 Diabetes Mellitus is an important risk factor for Alzheimer disease and vascular dementia. However, the association between Parkinson's disease and Diabetes Mellitus is controversial. Objective: To investigate glucose metabolism abnormalities in 110 Parkinson's disease patients with and without dementia. Subjects and Methods: We evaluated Insulin Resistance, glucose and insulin levels after a 2-h-oral-glucose-tolerance-test in 53 Parkinson's disease with dementia and 57 with Parkinson's disease without dementia, with normal fasting glucose. Results: BMI, waist circumference, fasting glucose and insulin values, HbA1c, triglycerides, blood lipid profile, depression rating, educational levels, levodopa-dosage and antipsychotic use were similar in both groups. Disease duration and motor impairment were higher in patients with Parkinson's disease and dementia group. After 2-h-oral-glucose-tolerance-test, the prevalence of glucose metabolism abnormalities was significantly higher in group with Parkinson's disease and dementia group (p = 0.03). The insulin resistance was present in 62% patients with Parkinson's disease with dementia, of whom 30% had also impaired glucose tolerance, 5,6% newly diagnosed Diabetes Mellitus and 26% only Insulin Resistance. These percentages were significantly higher in group with Parkinson's disease and dementia, also after adjustment for disease duration and motor disability. Conclusions: Our study suggests that PD patients with dementia are two times more likely to have insulin resistancethan patients with PD. © 2011 Elsevier B.V. All rights reserved.