Postprandial plasma glucose excursions and cognitive functioning in aged type 2 diabetics

BACKGROUND: Postprandial plasma glucose (PPG) excursion is a significant determinant of overall metabolic control as well as an increased risk for diabetic complications. Older persons with type 2 diabetes mellitus (DM2) are more likely to have moderate cognitive deficits and neurophysiologic and structural changes in brain tissue. Considering that poor metabolic control is considered a deranging factor for tissue/organ damage in diabetics, the authors hypothesized that PPG excursion is associated with a decline in cognitive functioning and that a tighter control of PPG may prevent cognitive decline. METHODS: Two groups of aged diabetic patients were randomly selected to be treated with repaglinide (n = 77) or glibenclamide (n = 79). RESULTS: Coefficient of variation of PPG (CV-PPG) was associated with Mini-Mental State Examination (MMSE) scores (r = -0.3410; p < 0.001) and a composite score of executive and attention functioning (r = -0.3744; p < 0.001) after adjusting for multiple confounders. Both groups showed a significant decline in hemoglobin A1c (HbA1c) and fasting plasma glucose (FPG), but only the repaglinide group demonstrated a significant decline of CV-PPG over time. In models investigating the change in cognitive functioning over time, adjusted for HbA1c and CV-FPG, a decline in cognitive functioning was observed only in the glibenclamide group (p < 0.001). After adjusting for CV-PPG, the authors no longer found a decline in executive and attention functioning composite score (p = 0.085) or the MMSE (p = 0.080) with glibenclamide. CONCLUSIONS: Exaggerated postprandial glucose (PPG) excursions are associated with a derangement of both global, executive, and attention functioning. A tighter control of PPG may prevent cognitive decline in older diabetic individuals.