The effect of long-term past glycemic control on executive function among patients with type 2 diabetes mellitus.

OBJECTIVE: Patients with type 2 diabetes mellitus (T2DM) show more executive dysfunction than nondiabetics. However, how long poor glycemic control affects executive function remains unclear. Thus, we aimed to investigate the relationships in a cross-sectional study. METHODS: We studied 118 T2DM outpatients (age, ≥ 60 years; excluding history of stroke, dementia and severe hypoglycemia). HbA1c values were recorded every ≤ 12 weeks for ≥ 5 years. All patients underwent verbal-fluency tests (reflecting executive function) and Mini-Mental State Examination (MMSE). The correlation between past glycemic control values and both cognitive tests scores was investigated. As markers of past glycemic control, we used average hemoglobin A1c (HbA1c) values and glycemic control variability [coefficient of variation (CV) of HbA1c values (HbA1c-CV)]. RESULTS: Verbal-fluency tests scores correlated with HbA1c-CV, but not with average HbA1c values, after adjusting for age, years of education and sex. Verbal-fluency tests scores correlated with HbA1c-CV for the past 5 years, best compared with HbA1c-CV for past < 5 years. MMSE scores were also related to only HbA1c-CV for the past 3 years in an adjustment model. CONCLUSIONS: Five-year HbA1c variability affected executive function in T2DM patients, but not average HbA1c values. Long-term longitudinal studies may be required.

Predicting the ability of elderly diabetes patients to acquire the insulin self-injection technique based on the number of animal names recalled.

AIMS/INTRODUCTION: To our knowledge, no studies have reported that cognitive tests can be used to evaluate whether or not patients can acquire the insulin self-injection technique. We investigated whether or not the number of animal names recalled in 1 min by elderly diabetes patients could be used as a predictor of the patients' ability to acquire the insulin self-injection technique within 1 week. MATERIALS AND METHODS: We enrolled 57 inpatients with type 2 diabetes aged >60 years who were starting insulin therapy. We carried out the Mini-Mental State Examination and verbal fluency tests, which included recalling animal names and common nouns starting with the letters 'a,' 'ka' and 'shi' (Japanese letters). We used 12 checkpoints for insulin self-injection to judge the patients' levels of acquisition of the technique. The most predictive cognitive test was determined by multivariate logistic regression analysis. RESULTS: In the present study, multivariate logistic analysis showed that the number of animal names recalled was the most reliable predictor of the ability to acquire the insulin self-injection technique within 1 week. A figure of 11 animal names predicted a successful acquisition, with a sensitivity of 73% and a specificity of 91% being observed (area under the curve 0.87, 95% confidence interval 0.76-0.97, P < 0.01). CONCLUSIONS: The number of animal names recalled in 1 min was the most useful indicator of the ability of elderly diabetes patients to learn to manage insulin self-injection therapy within 1 week. The cut-off value was 11 animal names.