Higher average blood glucose (sugar) levels in people with type 2 diabetes are linked to lower cognitive functioning, according to a study published online today in the journal Diabetes Care, published by the American Diabetes Association.

The ongoing Memory in Diabetes (MIND) study, a sub-study of the Action to Control Cardiovascular Risk in Diabetes (ACCORD) trial, found that higher levels of hemoglobin A1C levels (a measure of the average blood glucose levels over a 2-3 month period) are significantly associated with poorer performance on three cognitive tasks, which require memory, speed and the ability to manage multiple tasks at the same time. A higher A1C level was also associated with a lower score on a test of global cognitive function. Previous studies have shown that people with diabetes are 1.5 times more likely to experience cognitive decline and dementia than people without diabetes. The MIND results suggest diabetes may be associated with mild cognitive impairment.

"Even a mild impairment in cognitive function is of concern for people with type 2 diabetes," said lead researcher Dr. Tali Cukierman-Yaffe, of the Gertner Institute for Epidemiology & Health Policy Research, Endocrinology Institute at Sheba Medical Center & Sackler School of Medicine at Tel-Aviv University in Israel. However, these results are cross-sectional so it is not yet known whether higher levels of blood sugar increase the risk for cognitive impairment or whether impairment decreases the ability to control blood sugar levels. This will be answered in the ongoing ACCORD-MIND study, in which study patients are followed over time and are tested three times during the trial. One aim of this ACCORD-MIND follow-up is to test the hypothesis that lowering A1C could result in improved cognitive function.