BMI and Stroke Risk among Type 2 Diabetes Patients

There might be an association between obesity with incidence of stroke among type 2 diabetic patients…

Diabetes mellitus and obesity are the most common conditions that increase the risk of stroke in the general population. However, not many studies focused on the association between obesity and cardiovascular disease risk among patients with diabetes mellitus type 2. The goal of this study was to analyze the association between different levels of BMI at baseline, during follow-up, and at the last visit with stroke risk among type 2 diabetic patients in the Louisiana State University (LSU) Hospital-Based Longitudinal Study.

A prospective cohort study was performed with 29,554 newly diagnosed type 2 diabetic patients. Individuals with a history of stroke, coronary heart disease, or with incomplete data for analysis were excluded. The Cox proportional hazard regression models were used to estimate the association between BMI and risk of stroke. To avoid potential bias, additional analyses were also performed after excluding the patients who died or fell on the exclusion criteria during follow-up.

After 8.3 years follow-up period, a total of 2,883 participants developed stroke, with 2,821 ischemic and 109 hemorrhagic. The multivariable-adjusted (age, sex, race, smoking, income, and type of insurance) hazard ratios associated with different levels of BMI at baseline (18.5–24.9 [reference group], 25–29.9, 30–34.9, 35–39.9, and ≥40 kg/m2) were 1.00, 0.86, 0.83, 0.76, and 0.70 (P <0.001) for total stroke, 1.00, 0.87, 0.85, 0.78, and 0.72 (P <0.001) for ischemic stroke, and 1.00, 0.76, 0.72, 0.54, and 0.53 (P =0.034) for hemorrhagic stroke, respectively. When BMI was analyzed as a continuous variable, for each 1-U increase in BMI at baseline, the multivariable-adjusted hazard ratios were 0.986 (95% confidence interval [CI], 0.981–0.991) for total stroke, 0.987 (95% CI, 0.982–0.992) for ischemic stroke, and 0.978 (95% CI, 0.954–1.004) for hemorrhagic stroke, respectively (all P <0.05). In addition, there was no change in this inverse association of BMI with stroke risk when using an updated mean or the last visit value of BMI. This inverse association was consistent among patients with different ages, sex, races, HbA1c levels (<7% and ≥7%), never and current smoking, and using or not using glucose-lowering, cholesterol-lowering, or antihypertensive agents (all P <0.05). Moreover, there was a stronger inverse association of BMI and stroke risk among patients using or not using oral hypoglycemic agents compared to those using insulin (all P interaction<0.05). This stronger inverse association was also seen among patients with HbA1C levels <7% compared to those with HbA1C levels ≥7% (all P interaction<0.05).

This study showed an inverse association of BMI measurements at baseline, during follow-up, and at the last visit with the risks of ischemic and hemorrhagic stroke among type 2 diabetic patients. This association was consistent among patients of different ages, sex, never smoking and current smoking, and using or not using glucose-lowering agents. Due to several selection biases and some confounding factors, further research studies are needed to analyze this inverse association.

Practice Pearls:

• Intensive lifestyle intervention focusing on weight loss does not reduce the rate of cardiovascular events in obese diabetic patients, according to recent findings.
• The association of BMI with stroke risk was not significant among diabetic patients using insulin during follow-up.
• Results of this study might not be generalizable to the whole population due to a non-representative sample, several selection biases, and some confounding factors.

Weiqin Li, Peter T. Katzmarzyk, Ronald Horswell, Yonggang Zhang, Wenhui Zhao, Yujie Wang, Jolene Johnson, Gang Hu. Body Mass Index and Stroke Risk Among Patients With Type 2 Diabetes Mellitus. Stroke. 2015;46:164-169.