Ramping up exercise levels might help patients with non-insulin dependent type 2 diabetes reduce their reliance on glucose-lowering medications, a study shows.
But higher levels of exercise may be needed to have an effect on cardiovascular risk factors, the findings in Mayo Clinic Proceedings suggest.
According to a secondary analysis on a Danish RCT comparing an intensive lifestyle intervention versus standard care, exercise volume is associated with discontinuation of glucose-lowering medications in a dose-dependent manner.
Patients in the intervention group with the lowest levels of exercise (178 mins/week) over the 12-month study period were more likely to reduce glucose-lowering medications compared to the standard care group (OR 12.1).
And those in the intermediate (median 296 mins/week) and upper tertiles of exercise volume (380 mins/week) had the highest odds of discontinuing treatment (OR 30.2 and 34.4 respectively) compared to controls.
“The numbers needed to treat in the lower, intermediate, and upper tertiles were 4, 3, and 2, respectively,” the study authors said.
HbA1c was reduced from baseline in the intermediate and upper tertiles but not the lowest tertile of exercise intervention.
Body weight, BMI and fat mass were also reduced with the intermediate and highest level of exercise, but the study found energy intake was not the driver.
Triglyceride levels and absolute fitness (VO2 max) improved in the upper tertile only.
“Our analysis revealed that a lifestyle intervention including exercise volumes in the lower tertile was sufficient to introduce discontinuation of treatment with glucose-lowering medication in nearly half the participants,” the study said.
“However, this exercise volume failed to improve any cardiovascular disease risk markers. The data indicate that to achieve discontinuation of treatment with glucose-lowering medications while simultaneously improving clinically important markers associated with risk for T2D-related complications, exercise volumes must approach the level of the intermediate tertile.”
The study authors noted there were doubts about the feasibility of patients maintaining such high volumes of exercise.
Dr Brett Gordon, senior lecturer in exercise physiology at La Trobe University, told the limbic it was “a leap too far” to say there was a clear difference between the number of people who discontinued medications in the lower and upper tertiles.
“I’ve interpreted it as basically there is no meaningful difference between the number of participants who discontinued their glucose lowering meds between any of the exercise volumes,” he said.
This might be due in part to the low numbers of participants – only 20 in each of the intervention tertiles and 31 in the standard care group, said Dr Gordon.
He noted that even patients in the lower tertile of exercise started at a relatively high exercise volume >300 mins/wk and were still above 150 mins/wk until about six months, before their exercise volume dramatically fell away.
“Those in middle and upper quartiles have been able to maintain that level of exercise,” he said.
Exercise and Sports Science Australia (ESSA) recommend people with diabetes participate in 150-300 mins of exercise per week, which includes at least two muscle strengthening sessions.
“That is also reinforced by Diabetes Australia and I am sure it is reinforced by the NHMRC and some of other bodies,” said Dr Gordon.
“Certainly if you can comply with the recommended amount of exercise, you are going to be doing your health a favour.”