To investigate if diabetes is more common in drug-induced parkinsonism patients. We performed a hospital-based retrospective case-control study on 44 drug-induced parkinsonism (DIP) patients, 177 Parkinson disease patients, and 176 acute stroke patients matched for age and sex who were seen over the same period at the same hospital. The frequency of diabetes, age-at onset and sex were compared between DIP and IPD or acute stroke. Multivariate analysis showed that patients with diabetes are more frequent in DIP compared with IPD (p<0.001, adjusted OR 5.48; 95% CI, 2.52-11.94). The frequency of diabetes in DIP was comparable to that in acute stroke patients (p=0.16, adjusted OR 0.62; 95% CI, 0.32-1.21). These data suggest that diabetes may be a risk factor for DIP. Drugs with dopamine receptor blocking potency should be avoided in elderly with diabetes.