Diabetes, glycaemia, and cognition-a secondary analysis of the Finnish Diabetes Prevention Study.

ABSTRACT

BACKGROUND: Type 2 diabetes is linked with cognitive dysfunction and dementia in epidemiological studies, but these observations are limited by lack of data on the exact timing of diabetes onset. We investigated diabetes, dysglycaemia, and cognition in the Finnish Diabetes Prevention Study, in which the timing and duration of diabetes are well documented. METHODS: The Finnish Diabetes Prevention Study comprised middle-aged, overweight participants with impaired glucose tolerance but no diabetes at baseline (n = 522), randomized to lifestyle intervention or a control group. After an intervention period (mean duration 4 years) and follow-up (additional 9 years), cognitive assessment with the CERAD test battery and Trail Making Test A (TMT) was executed twice within a 2-year interval. Of the 364 (70%) participants with cognitive assessments, 171 (47%) had developed diabetes. RESULTS: Cognitive function did not differ between those who developed diabetes and those who did not. Lower mean 2-h glucose at an oral glucose tolerance test (OGTT) and HbA1C during the intervention period predicted better performance in the TMT (p = 0.012 and 0.024, respectively). Those without diabetes or with short duration of diabetes improved in CERAD total score between the two assessments (p = 0.001) whereas those with long duration of diabetes did not (p = 0.844). CONCLUSIONS: Better glycemic control among persons with baseline impaired glucose tolerance predicted better cognitive performance 9 years later in this secondary analysis of the Finnish Diabetes Prevention Study population. In addition, learning effects in cognitive testing were not evident in people with long diabetes duration. Copyright © 2015 John Wiley & Sons, Ltd.