Association of Cycling With All-Cause and Cardiovascular Disease Mortality Among Persons With Diabetes: The European Prospective Investigation Into Cancer and Nutrition (EPIC) Study

Abstract

Importance: Premature death from all causes and cardiovascular disease (CVD) causes is higher among persons with diabetes.

Objective: To investigate the association between time spent cycling and all-cause and CVD mortality among persons with diabetes, as well as to evaluate the association between change in time spent cycling and risk of all-cause and CVD mortality.

Design, setting, and participants: This prospective cohort study included 7459 adults with diabetes from the European Prospective Investigation into Cancer and Nutrition study. Questionnaires regarding medical history, sociodemographic, and lifestyle information were administered in 10 Western European countries from 1992 through 2000 (baseline examination) and at a second examination 5 years after baseline. A total of 5423 participants with diabetes completed both examinations. The final updated primary analysis was conducted on November 13, 2020.

Exposures: The primary exposure was self-reported time spent cycling per week at the baseline examination. The secondary exposure was change in cycling status from baseline to the second examination.

Main outcomes and measures: The primary and secondary outcomes were all-cause and CVD mortality, respectively, adjusted for other physical activity modalities, diabetes duration, and sociodemographic and lifestyle factors.

Results: Of the 7459 adults with diabetes included in the analysis, the mean (SD) age was 55.9 (7.7) years, and 3924 (52.6%) were female. During 110 944 person-years of follow-up, 1673 deaths from all causes were registered. Compared with the reference group of people who reported no cycling at baseline (0 min/wk), the multivariable-adjusted hazard ratios for all-cause mortality were 0.78 (95% CI, 0.61-0.99), 0.76 (95% CI, 0.65-0.88), 0.68 (95% CI, 0.57-0.82), and 0.76 (95% CI, 0.63-0.91) for cycling 1 to 59, 60 to 149, 150 to 299, and 300 or more min/wk, respectively. In an analysis of change in time spent cycling with 57 802 person-years of follow-up, a total of 975 deaths from all causes were recorded. Compared with people who reported no cycling at both examinations, the multivariable-adjusted hazard ratios for all-cause mortality were 0.90 (95% CI, 0.71-1.14) in those who cycled and then stopped, 0.65 (95% CI, 0.46-0.92) in initial noncyclists who started cycling, and 0.65 (95% CI, 0.53-0.80) for people who reported cycling at both examinations. Similar results were observed for CVD mortality.

Conclusion and relevance: In this cohort study, cycling was associated with lower all-cause and CVD mortality risk among people with diabetes independent of practicing other types of physical activity. Participants who took up cycling between the baseline and second examination had a considerably lower risk of both all-cause and CVD mortality compared with consistent noncyclists.

Figure 1.. Post hoc Analyses of the Associations Between Cycling or Leisure-Time Physical Activity (LTPA) (Excluding Cycling) and All-Cause or Cardiovascular Disease (CVD) Mortality

Solid lines are hazard ratios, and shading is the upper and lower bounds of the 95% CIs. Restricted cubic splines were applied (knot placements in the analyses were 0.5, 2.0, and 7.5 h/wk, and 21.1, 74.3, and 150.8 metabolic equivalent of tasks in hours per week [MET-h/wk] for cycling and LTPA, respectively). The MET-h/wk for cycling can be calculated based on the Compendium of Physical Activities using the code 01015 “Bicycling, general” with an estimated intensity of 7.5 MET-h. To convert hours of cycling to MET-h, multiply by 7.5. The corresponding MET-h values for 2, 4, 6, 8, and 10 hours of weekly cycling are 15, 30, 45, 60, and 75, respectively.

Figure 2.. Association Between All-Cause or Cardiovascular Disease (CVD) Mortality and Changes in Cycling From Baseline to the Second Examination

Among noncyclists, those who stopped cycling, those who started cycling, and those who maintained cycling, person-years of follow-up were 35 674, 5923, 3571, and 12 635, respectively; cases of all-cause mortality were 598, 138, 49, and 190, respectively; and cases of CVD mortality were 247, 78, 19, and 85, respectively. Median (interquartile range) minutes of weekly cycling at baseline were 0 (0-0), 90 (60-180), 0 (0-0), and 150 (90-300) minutes for noncyclists, those who stopped cycling, those who started cycling, or those who maintained cycling, respectively. Median (interquartile range) minutes of weekly cycling at the second survey were 0 (0-0), 0 (0-0), 90 (60-210), and 150 (90-300) minutes for noncyclists, those who stopped cycling, those who started cycling, or those who maintained cycling, respectively. All-cause mortality rates per 1000 person-years were 16.8 (95% CI, 15.5-18.2), 23.3 (95% CI, 19.7-27.5), 13.7 (95% CI, 10.4-18.2), and 15.0 (95% CI, 13.0-17.3) for noncyclists, those who stopped cycling, those who started cycling, or those who maintained cycling, respectively; the corresponding incidence rates per 1000 person-years for CVD mortality were 7.0 (95% CI, 6.1-7.8), 13.2 (95% CI, 10.6-16.4), 5.3 (95% CI, 3.4-8.3), and 6.7 (95% CI, 5.4-8.3), respectively. Model 1 was stratified by study center and adjusted for sex and age (second examination). Model 2 was stratified according to study center, baseline adherence to the Mediterranean diet, baseline occupational physical activity, and total energy intake, and adjusted for sex, age (second examination), baseline educational level, smoking status at both surveys, diabetes duration at the second survey, leisure-time physical activity (excluding cycling) at both examinations, and occupational physical activity at the second examination.