Exercise "blood sugar", air pollution "sugar rise", then on big "dirty" days exercise will increase or reduce the risk of diabetes? More than 350,000 people in prospective research tells you the answer!

The global burden of T2D has increased over the past few decades, and its prevention is a public health priority
.
It has been suggested that physical activity plays an important role
in the prevention of T2D and related diseases.
In contrast, exposure to air pollution was associated with
an increased risk of T2D.
Since PA increases respiration rate, the intake of polluted air during outdoor PA may increase significantly and may exacerbate the harmful health effects
of air pollution.
Therefore, it is of great public health significance
to study the trade-off between the health benefits of PA and the harmful effects of air pollution on T2D during PA.

To address this, the researchers used data from the UK Biobank, a large-scale prospective population-based cohort study to analyze the frequency and duration of PAs, long-term exposure to air pollution, and their association
with T2D risk.
The impact of
air pollution on T2D was comprehensively examined by assessing exposure to PM2.
5, PM≤10 (PM 10), PM2.
5 to₁₀ μm (_coarse PM) and_NO2.
In addition, given that genetic variation may alter the relationship between environmental factors and T2D risk, the researchers also explored the interaction
between PA or air pollution and T2D genetic risk.

The study ultimately included 359153 participants, with a mean (SD) age of 56.
3 (8.
1) years, and 52.
8% were women
.
Most participants (50.
4%) received moderate physical activity (600-3000 MET-min/wk).

The corrected HR for T2D in the moderate and severe air pollution groups were PM2.
5 1.
07 (95% CI, 1.
02–1.
11) and 1.
19 (95% CI 1.
14–1.
24), PM coarse 1.
02 (95% CI, 0.
98–1.
07) and 1.
06 (95% CI 1.
02–1.
15), PM10 1.
06 (95% CI 1.
02–1.
11) and 1.
13 (95% CI 1.
08–1.
15) compared to the low air pollution group, respectively, PM coarse 1.
02 (95% CI 1.
02–1.
07) and 1.
06 (95% CI 1.
02–1.
15), PM10 1.
06 (95% CI 1.
02–1.
11) and 1.
13 (95% CI 1.
08– 1.
18), NO2 1.
08 (95% CI 1.
04–1.
13) and 1.
19 (95% CI 1.
14–1.
28).

In addition, the researchers found a significant trend in T2D event associations between PA categories and all air pollution variables (Table 2).

Table 3 shows the association
between PAs stratified by individual air pollution variables and event T2D.
Stratified analysis showed that PA was negatively correlated
with the risk of T2D in each air pollution group.
At different levels for each air pollutant, high levels of PA were associated with a 25-28% reduction in T2D risk compared to low levels of PA (HR between 0.
72 and 0.
75).

There was no significant interaction between PA and air pollution (all interactions P>0.
05).

Figure 1 shows the joint association
of PA and air pollution with T2D risk.
The analysis showed that participants in the high PA and low air pollution groups had the lowest
risk of T2D.
Compared with the low PA group and high air pollution group, the T2D HR was 0.
61 (95% CI: 0.
57-0.
67) in the high PA group in the low PM2.
5 group, 0.
69 (95% CI: 0.
64-0.
75) in the low PM10 group, and 0.
63 (95% CI: 0.
58-0.
69)
in the low NO2 group.
The negative correlation between PA and T2D in each atmospheric pollution layer was basically consistent (trend P was <0.
05).

Genetic data
from 351185 participants in this study.
In multivariate adjusted models, participants with moderate (HR: 1.
45, 95% CI: 1.
38-1.
52) or high (HR: 2.
20, 95% CI: 2.
10-2.
30) T2D GRS had an increased
risk of T2D compared with participants with low T2D GRS.
In the combined effects analysis, PA and individual air pollution variables were significantly associated with T2D risk and were independent of T2D GRS (Figure 2).

There was no significant interaction between PA or air pollutants and T2D GRS (all interactions P>0.
05), indicating that the association with PA and air pollutants did not change
significantly on the basis of genetic risk.

Overall, the results of this large-scale prospective cohort study suggest that higher PA and lower air pollution levels are independently associated with lower T2D risk, and that the benefits of PA for T2D remained generally stable
among participants exposed to different levels of air pollution variables, including PM2.
5, crude PM, PM10, and NO2.
The results of this study suggest that PA for T2D
prevention should be promoted in populations with relatively high and low levels of air pollution exposure.
Further research is needed to validate our findings
in moderately and severely contaminated areas.

Original source:

Li ZH, Zhong WF, Zhang XR, Chung VC, Song WQ, Chen Q, Wang XM, Huang QM, Shen D, Zhang PD, Liu D, Zhang YJ, Chen PL, Cheng X, Yang HL, Cai MC, Gao X, Kraus VB, Mao C.
Association of physical activity and air pollution exposure with the risk of type 2 diabetes: a large population-based prospective cohort study.
Environ Health.
2022 Nov 6; 21(1):106.
doi: 10.
1186/s12940-022-00922-3.
PMID: 36336676; PMCID: PMC9639290.