Diabetes mellitus and progression of rigidity and gait disturbance in older persons

Background: Parkinsonian-like signs, including rigidity, gait disturbance, and bradykinesia, are common and progressive in old age and are associated with morbidity and mortality. Few risk factors for these signs have been identified. Diabetes mellitus, also a common chronic condition in old age and known to be associated with physical and neurologic disability, may be associated with parkinsonian-like signs. Objective: To examine the relation of diabetes to four parkinsonian-like signs. Methods: Participants were 822 older Catholic clergymen and women who were without clinically diagnosed Parkinson disease or dementia at baseline. For up to 9 years, they had uniform annual evaluations, which included a modified version of the motor portion of the Unified Parkinson's Disease Rating Scale, from which previously established measures of four specific parkinsonian-like signs were derived. Participants were evaluated for the presence of diabetes, based on direct medication inspection and history. Results: Diabetes was present in 128 (15.6%) participants. In random effects models controlling for age, sex, and education, diabetes was associated with worsening rigidity (p<0.01) and gait (p<0.05), over an average of 5.6 years of follow-up, but not with change in bradykinesia or tremor. The presence of stroke did not substantially affect the association of diabetes with rigidity but reduced the association of diabetes with gait to a trend (p=0.08). Conclusion: Diabetes may be a previously unrecognized risk factor for progression of parkinsonian-like signs in older persons.