Association between improvements in insulin resistance and changes in cognitive function in elderly diabetic patients with normal cognitive function

AIM: The number of elderly with cognitive dysfunction has been increasing in developed countries. Several studies have shown that diabetes is a risk factor for declines in cognitive function and, recently, numerous studies have demonstrated that exercise improves insulin resistance (IR). However, no studies have been undertaken to examine the relationship between IR and cognitive dysfunction. METHODS: Sixteen elderly diabetic patients participated in this study (mean age 70.9 ± 3.7 years). They were divided into control and training groups, and the training group was instructed to exercise 4 days per week for 12 weeks using horse riding simulation equipment (JOBA). Insulin sensitivity was measured by the euglycemic clamp technique and several tests to assess cognitive function, such as the Mini-Mental State Examination (MMSE), were performed. RESULTS: There were no statistically significant differences between the control and training groups in the baseline data. The differences of glucose infusion rate values and delayed word list scores, between baseline and the follow up, were significantly correlated (P = 0.024). In addition, changes in fasting blood sugar (FBS) and in the Trail Making Test B (TMT-B) score were also correlated (P = 0.035). CONCLUSION: The current study showed that a 12-week exercise intervention program did not significantly improve IR in elderly diabetic patients. However, changes in IR were associated with improvements in memory function, and reduced FBS was associated with improvements in TMT-B.