Spotlight on stroke risk

The effect of hyperglycemia on stroke risk was examined by several studies published in the past month.

Diabetes increases the risk of stroke more for women than for men, according to a systematic review and meta-analysis published online by The Lancet March 7. The analysis of 64 studies, including more than 12,000 strokes, found diabetic women's relative risk (RR) of stroke was 2.28 (95% CI, 1.93 to 2.69), compared with diabetic men's RR of 1.83 (95% CI, 1.60 to 2.08). Thus, women had a 27% greater RR for stroke, even after controlling for baseline differences in major cardiovascular risk factors. The authors speculated that women may have greater deterioration in their cardiovascular function before development of overt diabetes and that a sex-specific intervention in prediabetic women could have substantial effect on vascular events.

Another group of researchers conducted a prospective study of stroke risk in patients already diagnosed with type 2 diabetes. Their study, published by Diabetologia Feb. 24, included 20,000 patients with about 3,000 incident strokes and compared HbA1c levels with stroke risk. In women, they found a graded association between increasing glycemia and stroke risk: For example, compared to women with an HbA1c of 6.0% to 6.9%, those with an HbA1c of 10% or higher had adjusted hazard ratio for stroke of 1.42 (95% CI, 1.23 to 1.65). The trend was particularly significant in women older than 55. No such trend was found in men. These findings contrast with the same researchers' earlier work in which they had found a graded positive association between HbA1c and heart disease in both women and men.

The relationship between cerebral white matter disease (WMD) identified on an MRI and HbA1c was explored in a study of 512 patients with a first acute ischemic stroke, published in Stroke on Feb. 25. White matter disease is the name given to hyperintense changes seen on T2 imaging on MRI scans. The pathophysiology (or significance) of WMD is not entirely clear but previous work suggests it may relate to chronic ischemia and associates it with age and hypertension. The authors performed MRIs on all the stroke patients, and almost 90% patients were found to have WMD. Using multiple regression analysis, the authors found more WMD after stroke to be associated with increasing age, arterial hypertension, and HbA1c. The analysis suggested that even prediabetic glucose levels might increase the risk of WMD and the authors called for additional studies to investigate.