Researchers from the University of California analysed data from 15 prospective cohort studies (n=760 925) in order to examine if there is a link between pre-diabetes and an increased risk of stroke.
The results, published in the BMJ, showed a link between stroke and pre-diabetes – but that relationship depended on the definition of pre-diabetes.
In eight of the studies examined, pre-diabetes was defined as fasting glucose 100–125 mg/dL (5.6–6.9 mmol/L) and there was no increased risk of stroke after adjustment for established cardiovascular risk factors.
However, there was an increased risk of stroke in studies where pre-diabetes was defined as fasting glucose 110–125 mg/dL (6.1–6.9 mmol/L).
If the 1997 American Diabetes Association definition (ADA) of 110–125 mg/dL (6.1–6.9 mmol/L) was used, then pre-diabetes carried a 21% higher chance of stroke. However, in 2003 the ADA redefined pre-diabetes as an impaired fasting glucose of 100 to 125mg/dL and no risk was found in studies using this current, less stringent definition.
The authors stressed the possibility that some other unmeasured (confounding) factor may explain these results and it is important to note that the quality of evidence was variable.
The authors suggest that those with pre-diabetes should be aware that they are at increased risk of future stroke and that the condition is associated with the presence of one or more other cardiovascular risk factors. They recommend that weight be kept under control and that healthy lifestyle changes should be adopted to decrease this risk.
