The joint association of physical activity and glycaemic control in predicting cardiovascular death and all-cause mortality in the US population

The aim of this study was to examine the joint association of physical activity and glycaemic control as measured by HbA_1c on all-cause and cardiovascular disease (CVD) mortality risk.

The sample included 10,352 adults from the Third National Health and Nutrition Examination Survey (NHANES III) Linked Mortality Public-use File (follow-up 13.4 ± 3.9 years; 2,463 deaths). Physical activity was assessed by questionnaire and classified into inactive and active categories based on self-reported frequency of leisure-time activity. HbA_1c was categorised to reflect the American Diabetes Association diagnostic and treatment guidelines.

Being physically active was associated with a decreased risk of all-cause (HR 0.74 [95% CI 0.67, 0.81]) and CVD (HR 0.71 [95% CI 0.62, 0.82]) mortality, whereas higher levels of HbA_1c were associated with an increased mortality risk. HbA_1c ≥7% (53 mmol/mol) was associated with the highest risk for all-cause (HR 1.54 [95% CI 1.30, 1.82]) and CVD (HR 1.93 [95% CI 1.52, 2.45]) mortality. Across all categories of HbA_1c, active individuals were not at increased risk for all-cause mortality compared with inactive individuals with normal glycaemic control. Similar findings were observed for CVD mortality, except that active individuals with HbA_1c ≥7% (53 mmol/mol) were still at increased risk for CVD mortality. However, their risk for CVD death was substantially lower than the risk for their inactive counterparts (HR 1.38 [95% CI 1.03, 1.84] vs HR 1.98 [95% CI 1.34, 2.92]).

Physical activity is associated with lower all-cause and CVD mortality risk for individuals across all levels of glycaemic control. Therefore, engaging in a physically active lifestyle and achieving normal levels of glycaemic control may both be important for the prevention of early mortality.