For adolescents, low cardiorespiratory fitness and poor muscle strength increase their risk for type 2 diabetes later in life, regardless of body weight, according to a study of young men in Sweden.

“Not only were both low aerobic and muscular fitness linked with a higher long-term risk of diabetes, but this was true even among those with normal body mass index,” said lead author of the study Dr Casey Crump of the Icahn School of Medicine at Mount Sinai in New York City

These risk factors had a synergistic effect. In other words, the combination of low aerobic and muscular fitness increased diabetes risk more than the sum of the two individual risks.

The researchers used data on more than one million 18-year-old military conscripts in Sweden between 1969 and 1997, without a history of diabetes.

The researchers followed these men until 2012, identifying type 2 diabetes diagnoses using national hospital and outpatient registries.

About 2%, or 34,000 men, were diagnosed with diabetes during follow-up, which lasted into middle age for most. Half were diagnosed after age 46.

Those who were least fit as 18-year olds were three times more likely to be diagnosed with diabetes than those with better measures of aerobic capacity and strength, even for young men with a healthy body mass index.

Current US guidelines recommend 60 minutes of exercise daily, most of which should be aerobic activity, but should also include muscle-strengthening activities at least three days per week, but only about half of U.S. children and youth meet these guidelines.

Source: Annals of Internal Medicine