Teenagers with poor fitness and muscle strength could be at greater risk of type 2 diabetes in later life, regardless of body weight, according to research.
The Swedish study looked at 1.5 million 18-year-old military recruits between 1969 and 1997 who, at the time, did not have diabetes.
The participants were followed by researchers until 2012 by using type 2 diabetes diagnoses via national hospital and outpatient registries.
The findings showed that those with low aerobic capacity and muscle strength were three times more likely to be diagnosed with type 2 diabetes.
Speaking to Reuters news agency, study lead Dr Casey Crump, Icahn School of Medicine at Mount Sinai in New York City, said: “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.
“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 research published in Annals of Internal Medicine showed that about 34,000 men were diagnosed with type 2 diabetes. Half were diagnosed after the age of 46.
The participants were subjected to standardised tests which measured their aerobic capacity and muscle strength.
Researchers said this is one of the first studies to examine fitness, rather than self-reported levels of activity.
Dr Crump said: “More studies will be needed that measure physical fitness as well as diet and body mass index (BMI) at other time points across the lifespan to examine age windows of susceptibility to these factors in relation to diabetes.
“Young people should maintain regular exercise and both aerobic and muscular fitness, and avoid barriers to this such as screen time.”
Current NHS guidelines state that adults aged between 19 and 64 should try to get at least 150 minutes of moderate aerobic activity per week, such as cycling or fast walking, and strength exercises on two or more days a week.

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