Physical activity, long‐term fine particulate matter exposure and type 2 diabetes incidence: A prospective cohort study

Abstract

Background

Despite the adverse effects of ambient fine particulate matter (PM _2.5) on type 2 diabetes and the beneficial role of physical activity (PA), the influence of PM _2.5 on the relationship between PA and type 2 diabetes remains unclear.

Methods

In this prospective study with 71,689 participants, PA was assessed by a questionnaire and was categorized into quartiles for volume and three groups for intensity. Long‐term PM _2.5 exposure was calculated using 1‐km resolution satellite‐based PM _2.5 estimates. PM _2.5 exposure and PA's effect on type 2 diabetes were assessed by cohort‐stratified Cox proportional hazards models, individually and in combination.

Results

In 488,166 person‐years of follow‐up, 5487 incident type 2 diabetes cases were observed. The association between PA and type 2 diabetes was modified by PM _2.5. Compared with the lowest quartile of PA volume, the highest quartile was associated with reduced type 2 diabetes risk in low PM _2.5 stratification (≤65.02 µg/m ³) other than in high PM _2.5 stratification (>65.02 µg/m ³), with the hazard ratio (HR) of 0.75 (95% confidence interval [CI]: 0.66–0.85) and 1.10 (95% CI: 0.99–1.22), respectively. Similar results were observed for PA intensity. High PM _2.5 exposure combined with the highest PA levels increased the risk of type 2 diabetes the most (HR = 1.79, 95% CI: 1.59–2.01 for PA volume; HR = 1.82, 95% CI: 1.64–2.02 for PA intensity).

Conclusion

PA could reduce type 2 diabetes risk in low‐pollution areas, but high PM _2.5 exposure may weaken or even reverse the protective effects of PA. Safety and health benefits of PA should be thoroughly assessed for long‐term polluted residents.

Abstract

Exposure‐response relations of physical activity (PA) with type 2 diabetes were stratified by different levels of PM _2.5 exposure. The HRs for type 2 diabetes associated with PA volume (A) and PA intensity (B) were estimated by restricted cubic‐spline regression under low and high levels of PM _2.5. Solid lines represent HRs, and the shaded areas represent 95% confidence intervals. The models were adjusted for age, sex, urbanization, geographical region, education level, smoking status, alcohol drinking, family history of type 2 diabetes, body mass index, and baseline blood glucose level.

Key points

• PM _2.5 modifies the association between physical activity (PA) and type 2 diabetes.

• PA reduces type 2 diabetes risk at lower PM _2.5 stratum but increase at higher strata.

• The benefits of PA are weakened by the detrimental effects of PM _2.5 exposure.

• Call for consideration of the joint impact of PA and air pollution on health.