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Graded Association between Stroke Risk and HbA1c for Women

A graded association between HbA1c and stroke risk may exist among women…. 

In this prospective analysis, researchers investigated the sex-specific association among different levels of hemoglobin A1c along with incident stroke risk. Study participants included 19,278 female and 10,876 type 2 diabetic patients.

Among study participants 2,949 incident cases of stroke were found during an average follow-up of 6.7 years.

This graded positive association of HbA1c with stroke risk was confirmed among patients with diabetes whether or not they used glucose-lowering agents (P for trend < 0.05). The overall incidence of stroke was higher among men than women (16 per 1,000 person-years verses 13.9 per 1,000 person-years, respectively). The risk of stroke associated with HbA1c was higher in female than in male patient with diabetes (χ2 =7.85, df=1, P for interaction= 0.005)

In men, the multivariable-adjusted hazard ratios of stroke associated with different levels of HbA1c at baseline (HbA1c< 6.0%, 6.0 to 6.9%; 7.0 to 7.9%, 8.0 to 8.9%, 9.0 to 9.9% and ≥10.0%) were 0.96, 1.00, 1.04, 1.11, 1.10 and 1.22, respectively (P for trend = 0.66, CI 95%). Each 1% increase in baseline HbA1c was associated with a 1% increased risk of stroke in males (CI 95%, 0.99 to 1.04).

In women, the multivariable-adjusted hazard ratios of stroke associated with different levels of HbA1c at baseline (HbA1c < 6.0%, 6.0 to 6.9%; 7.0 to 7.9%, 8.0 to 8.9%, 9.0 to 9.9% and ≥10.0%) were 1.03, 1.00, 1.09, 1.19, 1.32 and 1.42, respectively (P for trend < 0.001).

A graded association between HbA1c and stroke risk was found in female study participants even when stratified by race or in the presence or absence of glucose-lowering agents (P-trend 0.066). Each 1% increase in baseline HbA1c was associated with a 5% increased risk of stroke in females (CI 95%, 1.02 to 1.07).

Adjusted Hazard ratios were significantly higher particularly in women ≥ 55 years old. When stratified by age, each 1% increase in HbA1c from baseline was associated with a 2% increase in risk for stroke in females aged < 55 years (CI 95%, 1.00 to 1.05). For women ≥ 55 years old, each 1% increase in HbA1c from baseline increased risk of stroke by 5% (CI 95%, 0.99 to 1.04).

Practice Pearls:
  • Type 2 diabetes in an independent risk factor for stroke
  • Poor control of blood sugar may have a stronger negative effect in diabetic women older than 55 years
  • Understanding risk factors can have positive implications for the prevention of stroke in particular populations and subpopulations of patients

Zhao W, Katzmarzyk PT, Horswell R, Wang Y, Johnson J, Hu G. Sex differences in the risk of stroke and HbA1c among diabetic patients. Diabetologia. 2014;57(5):918-26. Accessed online from: http://download.springer.com/static/pdf/809/art%253A10.1007%252Fs00125-014-3190-3.pdf?auth66=1398833836_e16e05f85f76d32db3e3aacd61706982&ext=.pdf