In people with diabetes, fat mass index, not body mass index (BMI), is associated with a higher risk of cardiovascular events, according to data drawn from the ACCORD randomised controlled trial in the US.
Heart disease is a major cause of death worldwide, and obesity is a major risk factor. Body mass index, a common measure of obesity, has been recently shown to be an imperfect metric because it does not distinguish between lean muscle mass and fat mass. When issues related to obesity are studied, suitable metrics that describe obesity accurately are extremely important.
Researchers analysed data on 10 251 adults from the ACCORD study, a randomised controlled trial in the US looking at diabetes and cardiovascular disease (CVD). The mean age was almost 63 years, and 62% of participants were men.
The researchers found that people with type 2 diabetes and higher fat mass were at increased risk of major cardiovascular events compared to people with lower fat mass. In contrast to previous research, the protective role of lean body mass was not observed in the research population with type 2 diabetes as a whole.
"We found that the protective effect of lean body mass was observed in participants with a lean BMI of less than 16.7 kg/m2," writes Dr Xinqun Hu, departments of cardiovascular medicine and emergency medicine, The Second Xiangya Hospital, Changsha, Hunan, China, with co-authors. "The increased risk of CVD in (type 2 diabetes mellitis) patients with lower BMI may be attributed to the adverse effect of lower lean body mass that overrides the positive effect of lower fat mass."
Background: Previous studies have found that predicted fat mass and lean body mass may act differently on adverse events. However, the cardiovascular prognostic value of lean body mass and fat mass in patients with type 2 diabetes mellitus (T2DM) has not yet been investigated. We sought to investigate the relation between predicted lean body mass or fat mass and the risk of cardiovascular disease in patients with T2DM.
Methods: We conducted a post hoc analysis of data from the Action to Control Cardiovascular Risk in Diabetes (ACCORD) study to investigate the relation between the predicted lean body mass or fat mass and major adverse cardiovascular events in patients with T2DM. We used sex-specific quartiles of predicted lean body mass index (BMI; kg/m2) and fat mass index (kg/m2). We defined a major adverse cardiovascular event as a composite of nonfatal myocardial infarction, nonfatal stroke or death from cardiovascular causes.
Results: After a mean follow-up period of 8.8 years, we found that a major cardiovascular event occurred in 1801 of 10 251 patients (17.8%). Predicted lean BMI was not associated with major cardiovascular events (p = 0.34). Compared with patients in the first quartile (incidence rate 16.4%; 17.2%, 17.5% and 19.8% for the second, third and four quartiles, respectively) of predicted fat mass index, those in the fourth quartile had a hazard ratio of 1.53 (95% confidence interval 1.23–1.91).
Interpretation: In patients with T2DM, we found that predicted fat mass had a strong positive association with a higher risk of a major adverse cardiovascular event. Increasing lean body mass did not have a protective role.
Zhenhua Xing, Liang Tang, Jian Chen, Junyu Pei, Pengfei Chen, Zhenfei Fang, Shenghua Zhou, Xinqun Hu