Hyperglycemia is known to cause microvascular damage, which then creates complications such as proliferative retinopathy. However, this microvascular damage may also affect cognitive functioning even before it is reflected by more easily observed complications such as retinopathy. A study carried out by Eelco van Duinkerken and colleagues in the Netherlands found that "functional connectivity", which is "an indicator of functional interactions and information exchange between brain regions," was different in type 1's as compared to controls.

The results were published in Diabetes, a journal of the American Diabetes Association, "Functional Brain Connectivity and Neurocognitive Functioning in Patients with Longstanding Type 1 Diabetes Mellitus with and without Microvascular Complications: a Magnetoencephalography Study".

Magnetoencephalography ("magneto" = magnetic; "encephalo" = brain; "graphy" = process of describing) is an imaging technique that measures the magnetic fields (yes, magnetic fields) produced by electrical activity in the brain. Super-sensitive devices called SQUIDs (superconducting quantum interference devices) are placed on the scalp and measure tiny fluctuations in magnetic fields through the skull.

Believe it or not, magnetic fields, tiny as they may be, are less distorted by the skull than the electrical fields that produce them. This allows better spatial resolution than simply recording electrical activity, so investigators can pinpoint what regions of the brain are communicating with each other.

By recording magnetic fluctuations during neuropsychological tests, researchers were able to make associations between cognitive functioning and functional connectivity.  They found that type 1's were different from controls in terms of executive functioning, memory, information processing speed, motor speed, and attention. The results were, for the most part, irrespective of microvascular complication status (in this study- whether or not subjects had proliferative retinopathy).

The authors conclude that chronic hyperglycemia may affect brain functioning even before microvascular damage can be observed.  Clearly, maintaining blood glucose levels as early and as effectively as possible, and preventing chronic hyperglycemia can help reduce the risk of cognitive dysfunction.

* * *

Sources:

American Diabetes Association

Article abstract: Diabetes