Elevated Fasting Blood Glucose Level Increases the Risk of Cognitive Decline Among Older Adults with Diabetes Mellitus: The Shanghai Aging Study

Background: Several studies have demonstrated that the elevated fasting blood glucose (FBG) may increase the risk of incident dementia in older adults with or without diabetes mellitus (DM). However, similar results are rarely reported in Chinese population. Objective: This study aimed to demonstrate the association between FBG and risk of incident cognitive decline in older Chinese adults. Methods: We prospectively followed up 1,555 dementia-free participants with baseline FBG measurement in the Shanghai Aging Study. Results: We identified 126 incident dementia cases across a mean of 5.2 years. Cumulative dementia incidence in type II DM participants with higher FBG (>6.1 mmol/L) increased most dramatically, second with that of non-DM participants with higher FBG, than that of participants with lower FBG (<= 6.1 mmol/L). DM participants had a significant higher risk of incident dementia (adjusted HR 1.51, 95%CI 1.25-1.82) by every 1 mmol/L increment of FBG. Among DM participants, baseline FBG was positively related to the rate of annual decline of MMSE (beta=0.10, p = 0.0018). Conclusions: Our results suggest that especially in people with type II DM, effective blood glucose control may help to prevent cognitive impairment in later life.