Aims/hypothesis  

The aim of the study was to assess the effect of hyperglycaemia on regional concentrations of glucose and other substrates within the brain in non-diabetic individuals and in patients with type 1 diabetes.

Methods  

The brain metabolites of 17 men with type 1 diabetes and 12 age-matched non-diabetic men (22–43 years old) were studied after an overnight fast (plasma glucose 9.2 ± 3.0 vs 4.8 ± 0.5 mmol/l, respectively). N-Acetylaspartate (NAA), creatine, choline, myo-inositol (mI) and glucose in the frontal cortex, frontal white matter and thalamus were quantified with proton magnetic resonance spectroscopy.

Results  

In the non-diabetic participants, the glucose level was 47% higher (p < 0.01) in the frontal cortex than in the frontal white matter. In contrast, this regional variation was not observed in the diabetic participants, in whom the glucose level in the frontal white matter was 64% higher (p < 0.001) and in the frontal cortex 25% higher (p = 0.033) than that of the non-diabetic participants. In the diabetic participants, the glucose level in each of the three regions studied correlated with fasting plasma glucose (r = 0.88–0.67, p < 0.01). In addition, in the diabetic participants, mI was 20% higher (p < 0.001) and NAA 6% lower (p = 0.037) in the frontal white matter, and mI was 8% higher (p = 0.042) in the frontal cortex, than in the non-diabetic participants.

Conclusions/interpretation  

In type 1 diabetes, hyperglycaemia is associated with accumulation of glucose and mI in the cortex and in the white matter.