Subclinical systemic microvascular dysfunction exists already in asymptomatic patients with type 1 diabetes. We hypothesized that microangiopathy, resulting from long-standing systemic hyperglycemia and hyperinsulinemia, may be generalized to the brain, resulting in changes in cerebral blood flow and metabolism in these patients. We performed dynamic [15O]H2O and [18F]-fluoro-2-deoxy-D-glucose ([18F]FDG) brain positron emission tomography (PET) scans to measure cerebral blood flow (CBF) and cerebral glucose metabolism (CMRglu), respectively, in 30 type 1 diabetic patients and 12 age-matched healthy controls after an overnight fast. Regions of interest were automatically delineated on co-registered MRI images and full kinetic analysis was performed. Plasma glucose and insulin levels were higher in patients versus controls. Total grey matter CBF was 9%, whereas CMRglu was 21% lower in type 1 diabetic versus control subjects. We conclude that at real-life fasting glucose and insulin levels, type 1 diabetes is associated with decreased resting cerebral glucose metabolism, that is only partially explained by the decreased CBF. These findings suggest that other mechanisms than generalized microangiopathy account for the altered CMRglu observed in well-controlled type 1 diabetes. (NCT00626080)
- Received August 25, 2012.
- Accepted March 18, 2013.
- © 2013 by the American Diabetes Association.
Readers may use this article as long as the work is properly cited, the use is educational and not for profit, and the work is not altered. See http://creativecommons.org/licenses/by-nc-nd/3.0/ for details.