Habitual cycling, whether as transportation to work or as a recreational activity, has been associated with lower risk of developing type 2 diabetes (T2D), according to an epidemiology paper in PLOS Medicine, which affirms that Type 2 diabetes is a lifestyle disease, brought on by too many calories and not enough exercise.

The cohort analysis, conducted by Martin Rasmussen of the University of Southern Denmark, and colleagues, included 24,623 men and 27,890 women from Denmark, recruited between the ages of 50 and 65, and compared the association between self-reported recreational and commuter cycling habits with

type 2 diabetes

incidence measured in the Danish National Diabetes Registry. Participants who cycled a lot were less likely to develop type 2 diabetes, and risk of developing

type 2 diabetes

decreased with longer time spent cycling per week.

More exercise means more fitness and therefore less type 2 diabetes.

Five years after they were initially recruited, participants were contacted for follow-up and their cycling habits were re-assessed. People who took up habitual cycling during this period were at 20% lower risk for

type 2 diabetes

than non-cyclists.

Even with an obvious hypothesis that is well-known, this kind of study suffers from unmeasured confounding, or bias due to patients with missing data, or because it is self-reported cycling behavior.

Rasmussen says, "We find it especially interesting that those who started cycling had a lower risk of type 2 diabetes, given that the study population were men and women of middle and old age. This emphasizes that even when entering elderly age, it is not too late to take up cycling to lower one's risk of chronic disease."