Glucoregulation has greater impact on cognitive performance than macro-vascular disease in men with type 2 diabetes: data from the Caerphilly study.
Gallacher JE., Pickering J., Elwood PC., Bayer AJ., Yarnell JW., Ben-Shlomo Y.
OBJECTIVE: To compare vascular and glucose related mechanisms of type 2 diabetes on cognitive performance. RESEARCH DESIGN AND METHODS: A cross-sectional observational study of type 2 diabetes defined by non insulin dependant self-report diabetes or fasting blood glucose < or = 7.0 mmol/l of 2205 men eligible for the third phase of the Caerphilly Collaborative Heart Disease Study. Men were aged 55-69 years at time of testing. Tests of cognitive function included NART (crystallised IQ), AH4 (fluid IQ), verbal fluency (executive function) Cambridge Cognitive Examination (CAMCOG) and Mini Mental State Examination (MMSE) (global function), four choice serial reaction time (psychomotor function) and memory. Men with prior stroke were omitted from the analysis. RESULTS: Men with diabetes showed cognitive deficits for verbal fluency, National Adult Reacting Test (NART) and AH4. Adjusting for vascular risk factors had minimal effect. Including blood glucose removed the deficit for verbal fluency and NART but the effect on AH4 score (-2.58; 95% CI: -5.0, -0.1, p = 0.039) was retained. More detailed analyses of AH4 score on men with diabetes showed a curvilinear relationship indicating that men with both low and high glucose levels had worse performance (AH4 = -66 + 80 log(e) glucose - 18 log(e )glucose(2); 95% CI: -29, -6; p=0.002). CONCLUSIONS: These data identify a direct effect of glucose regulation on cognitive performance associated with diabetes in a population sample. These data suggest that an effect of glucose regulation on cognitive performance in diabetes is distinct from any effect of macro-vascular disease.