Association between insulin resistance and cognitive function in elderly diabetic patients

Abstract

Background: Recently, cognitive impairment in elder diabetic subjects has sparked considerable interest. Insulin resistance (IR) is one of the central pathologies in diabetes mellitus, and several studies have shown that IR is associated with cognitive impairment in non‐diabetic elderly subjects. However, the involvement of IR in cognitive dysfunction in the diabetic elderly has remained to be elucidated.Methods: In the current study we measured IR with the euglycemic insulin clamp technique, and assessed cognitive function in 13 elderly diabetic patients (mean age, 69.1 ± 4.4). Several tests to assess cognitive function including Mini‐Mental State Examination (MMSE) were performed, and clinical indices were evaluated. IR was evaluated by metabolic clearance rates (MCR).Results: The Spearman’s rank correlation coefficient between MCR and MMSE scores was 0.587 (P = 0.035). When subjects were divided into two groups at the median MCR (5.0 mL/kg/min), the lower MCR (high IR) group (n = 5) had significantly lower MMSE scores than the higher group (n = 8). The Spearman’s rank correlation coefficient was –0.641 (P = 0.018) between hs‐CRP and MMSE scores. When subjects were divided into two groups at the median of high‐sensitivity C‐reactive protein (hs‐CRP) (594.0 µg/dL), the higher hs‐CRP group (n = 6) had significantly lower MMSE scores than the lower group (n = 7).Conclusion: The current study shows that higher IR measured with the euglycemic insulin clamp technique and higher hs‐CRP is associated with lower MMSE scores in non‐demented diabetic elderly patients.