New findings from two randomised trials suggest people with type 2 diabetes lose less of their abdominal fat through a prescribed exercise programme than do non-diabetics.
Despite similar fitness gains after six months of aerobic and resistance training, diabetics lost just 4% of their abdominal fat, on average, compared to 13% in the no-diabetes group. The difference seemed to be due to a large change in visceral fat among exercisers without diabetes, without a similar improvement in those with the disease.
Dr. Devon Dobrosielski of the Johns Hopkins School of Medicine in Baltimore presented the findings Thursday at the American College of Sports Medicine's annual meeting in San Francisco.
"It could be a combination of the disordered metabolism and some of the medications that our diabetics use that inhibits the ability to lose that component of fat," Dr Kerry Stewart, the study's senior author, told Reuters Health.
"Clinicians should still encourage diabetics to exercise, but there may be more of a need to use medications more readily to control things like blood pressure," said Dr Stewart, also from Johns Hopkins.
Participants had mild hypertension
The researchers enrolled 255 people with and without diabetes to participate in one of two studies comparing body fat changes achieved through an exercise intervention.
Supervised exercise training was done three times per week, with baseline and six-month abdominal fat measured with magnetic resonance imaging and a treadmill test used to determine peak oxygen uptake.
All the participants had mild hypertension at baseline.
Two hundred and seventeen participants completed the trials, including 113 with type 2 diabetes not requiring insulin. At baseline, there was no difference between people assigned to the exercise and control groups, but on average the diabetics were younger (56.4 vs. 63.7 yr), heavier (98.3 vs. 83.6 kg), and had more abdominal body fat (588.8 vs. 439.7 cm3) than nondiabetics.
After six months, there was no change on any of the measures in subjects assigned to the no-exercise control groups.
Oxygen consumption peaked
But after the exercise training, peak oxygen consumption (peak VO2) increased in both diabetics and non-diabetics by an average of 3.6 ml/kg/min, and weight decreased by 2.2 kg, on average (p < 0.01 for both).
Yet abdominal fat – specifically visceral fat – decreased significantly less among people with diabetes than those without the disease, after adjustments for baseline values, age, and fitness.
That meant people with diabetes would have to improve their VO2 max significantly more to see the same reduction in abdominal fat, according to Dr Dobrosielski.
The researchers pointed out this were an exercise-only intervention, and that it may not have been enough to target key fat areas in diabetics.
"Once you get diabetes, it's somewhat of an uphill battle so you have to throw more of the lifestyle changes at those individuals, along with the medicines," Dr Stewart said.
Push diabetics’ to exercise
But that doesn't mean clinicians shouldn't still be pushing exercise for their diabetic patients, researchers agreed.
"People with type 2 diabetes... their main goal is to do enough exercise and the right type of exercise to improve their insulin sensitivity," as well as incorporating other strategies to lose weight, said Dr. David Swain, an exercise scientist at Old Dominion University in Norfolk, Virginia.
"Based on this one particular study, even if their conclusion is valid, that does not mean that exercise is not helping these people," Dr Swain told Reuters Health.
He also said it's possible the diabetes and non-diabetes participants differed in what they ate, for example, during the course of the study and in response to increased exercise – and that could have affected changes in abdominal fat.
(Genevra Pittman, Reuters Health, June 2012)
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