The study found that being out of shape aerobically and having poor muscle strength made a young man 3 times more likely to develop diabetes as he got older.
If you’re not in shape at age 18, the odds are greater you’ll develop type 2 diabetes (T2D) as you get older—no matter what your weight in your late teens.
That’s the finding of researchers who examined a generation’s worth of records from Swedish military recruits. The team, led by Casey Crump, MD, PhD, first looked at fitness tests of recruits from 1969 through 1997—capturing 98% of the nation’s male population at age 18 without prior diabetes. The study was published Tuesday in the Annals of Internal Medicine.
Using medical records, the researchers were able to see which of the young men developed T2D over time and which ones didn’t. In total, the study captured 1,534,425 men who took the military physical; of these, 34,008 developed T2D during 39.4 million person-years of follow-up.
The ones who had trouble with muscle strength tests, and whose aerobic capacity was lacking as measured on a stationary bicycle, were more likely to develop the disease. Having poor aerobic capacity was the stronger indicator, the team found—but being deficient in both areas tripled a young man’s risk of developing T2D later on.
The difference in T2D incidence between the lowest and highest tertiles of both aerobic capacity and strength was 0.22% at 20 years of follow-up, and 0.76% at 30 years, and 3.97% at 40 years.
What’s more, the finding was independent of other factors—body mass index, family history, education level, or socioeconomic status.
The study’s lead author said the findings show that health evaluations for teens and young adults examine overall strength and cardiovascular fitness; focusing only on weight could be misleading. “Prevention of type 2 diabetes should begin early in life,” said Crump, of the Icahn School of Medicine at Mount Sinai, New York.
The study was funded by the National Institutes of Health.
Crump C, Sundquist J, Winkleby MA, Sieh W, Sundquist K. Physical fitness among Swedish military conscripts and long-term risk for type 2 diabetes mellitus: a cohort study [published online March 8, 2016]. Ann Intern Med. 2016; doi:10.7326/M15-2002.