Clinical backgrounds and morbidity of cognitive impairment in elderly diabetic patients

Despite numerous reports that have linked diabetes with cognitive impairment (CI), there are few studies that have attempted to clarify the morbidity of CI among elderly diabetic patients. The Mini-Mental State Examination (MMSE) was performed on 240 diabetic patients aged 65 years or older who had no diagnosis of dementia. The MMSE scores were 28-30 (normal range) in 151 patients (63%), 24-27 (suspected CI) in 77 (32%), and ≤ 23 (definite CI) in 12 (5%). Eight of the 12 patients with MMSE scores ≤ 23 underwent further detailed examination: the final diagnosis was Alzheimer's disease (AD) (N = 5), vascular dementia (N = 2), and mixed dementia (N = 1). Among 24 of the 77 patients with MMSE scores of 24-27 who were referred for further detailed examination, the final diagnosis was early AD (N = 5), cerebrovascular disease (CVD) (N = 10), and mild CI (N = 7). Only 2 of the patients were judged as being normal. The percentage of patients with a history of CVD, the rate of diuretic use, and the serum levels of non-high-density lipoprotein cholesterol were higher, and the percentage of patients with a history of habitual alcohol consumption was lower in the low MMSE score group than in the normal MMSE score group. Among elderly diabetic patients aged 65 years or older, 5% had evident CI and 32% had suspected CI. Medical staff involved in the care of diabetic patients should be highly aware of possible CI in this patient population.