Cognitive function in Japanese elderly with type 2 diabetes mellitus

The current study was conducted to investigate the cognitive function in Japanese elderly with type 2 diabetes mellitus (DM). Participants included 69 diabetic and 27 nondiabetic subjects (60 to 85 years old). The cognitive functional tests conducted were the Mini-Mental State Examination (MMSE), Word Lists Recall (immediate, delayed), Digit Symbol Test (Wechsler Adult Intelligence Scale-Revised [WAIS-R]), and the Stroop Color Word Test. Hemoglobin Alc (HbAlc) was measured as the index of glycemic control, and information about recent hypoglycemic episodes was gathered by using questionnaires. Student's t test showed that DM subjects had significantly lower scores in the MMSE (P< .01) and Digit Symbol Test (P < .05) than non-DM subjects. The scores of the Digit Symbol Test in diabetes subjects had a significant negative relationship with HbAlc (r = -.433; P < .001), and insulin-use had a significant relationship with the scores of the MMSE and Digit Symbol Test. Subjects in the DNI group were further divided by insulin use. Comparison of insulin-treated DM subjects, non-insulin-treated DM subjects, and nondiabetic subjects by analysis of variance followed by Bonferrom's post hoc test showed that insulin-treated DM subjects had significantly lower scores in the MMSE and Digit Symbol Tests than both non-insulin-treated DM subjects (P < .05) and nondiabetic subjects (P < .01). Our study suggests that Japanese elderly DM subjects, especially those with insulin treatment, have poor cognitive function. (C) 2004 Elsevier Inc. All rights reserved.