Sex differences in MI risk in type 2 diabetes explored
medwireNews: The excess risk for myocardial infarction (MI) associated with having diabetes may be greater in women than men, despite men having a higher frequency of events overall, shows research from the UK Biobank.
The study included 471,399 participants (average age 56 years, 56% women) who were followed up for an average of 8.9 years. During this time, the incidence of MI was markedly higher in men than women, at 25.4 versus 8.7 per 10,000 person–years in those without diabetes.
MI rates per 10,000 person–years were increased in both sexes among people with prediabetes or diabetes, but remained higher in men than women, at 29.7 versus 10.9 for those with prediabetes, 38.9 versus 14.3 for undiagnosed diabetes, and 46.1 versus 20.4 for previously diagnosed diabetes.
The baseline rates of prediabetes were 11.3% and 11.8% in men and women, respectively, with corresponding rates of 0.9% and 0.5% for undiagnosed diabetes and 6.0% and 3.5% for previously diagnosed diabetes.
Despite the higher absolute risk for MI in men than women, the presence of diabetes was associated with a 2.33-fold increased risk for MI in women, compared with a 1.81-fold increased risk in men. The ratio of hazard ratios for women versus men was 1.29, and this was statistically significant – in other words the effect of diabetes on the risk of MI was significantly greater in women than in men.
Sanne Peters (The George Institute for Global Health, Oxford, UK) and co-researchers suggest that sex differences in healthcare uptake and provision could help to explain this difference, and indeed previous research from England and Wales showed that women with diabetes were less likely than men to receive guideline-compliant treatment.
However, research from other countries has produced mixed results both with regard to sex differences in healthcare use and in cardiovascular disease risk in people with diabetes, says the team.
They instead point to a role for biologic sex differences, noting research showing “that the cardiovascular risk profile in women needs to deteriorate further than men before they develop overt diabetes,” meaning that “women may be exposed to adverse cardiovascular risk factors over a longer time period” and are therefore at higher risk by the time they develop diabetes.
Given the female-predominant effect of diabetes, Peters et al call it “surprising” that they found no sex difference for the association between glycated hemoglobin (HbA1c) levels and MI risk.
There was an 18% increase in risk for MI with each 1% increase in baseline HbA1c level, and this was exactly the same for men and women.
“Reasons for this apparent discrepancy warrant further investigation, ideally in studies with repeated HbA1c measurements so as to assess the potential impact of sex differences in glycemic control post baseline assessment,” the team concludes in Diabetes Care.
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