Exercise may not improve the control of type 2 diabetes in obese young people, according to the surprise findings of a new Irish study.
The research was conducted among patients aged 15 to 30 years attending Dublin's St James's Hospital. Two groups of patients were studied. All were obese, while one group also had type 2 diabetes.
All were put through an exercise programme over a three-month period. They undertook one hour of aerobic exercise, four times a week at the Metabolic Research Unit gym at St James's.
And while earlier research at the hospital had found short-term exercise training increased insulin sensitivity by more than 50 per cent in obese middle-aged patients with type 2 diabetes, this was not the case in the younger group.
However, the exercise programme did improve fitness levels by 20 per cent in the young people who were obese but did not have diabetes.
One of the study's authors, Prof John Nolan, said this was encouraging, as it could help prevent onset of type 2 diabetes in this particular group.
The report of the study, published in this month's Diabetologia, the journal of the European Association for the Study of Diabetes, states it is possible that the frequency and intensity of the exercise programme may simply have been insufficient for the improvements that were expected.
"However, previous studies, including our own in equally obese but older subjects with obesity and type 2 diabetes, have shown improvements in insulin sensitivity and glycaemic control with similar or even less rigorous exercise regimes," the report says.
It also notes certain individuals may be genetically predisposed not to respond to exercise. While this was not examined among patients in the current study, it will be at a later stage.
A total of 21 young obese patients completed the exercise programme in this study - seven had type 2 diabetes.
While the study was small in scale, an editorial in Diabetologiasays it nonetheless raises "intriguing questions regarding the efficacy of exercise training for improvement of insulin sensitivity" in young obese people with early onset type 2 diabetes.
But it says the study should not, on its own, distract attention from the fact that evidence exists to show exercise is useful in the management and prevention of type 2 diabetes in many patients.
Prof Nolan said he hoped the findings would allow doctors better customise prevention and treatment for those at risk of type 2 diabetes.