Aerobic exercise and the lipid profile in type 1 diabetic men: a randomized controlled trial

Despite the potential importance of favorable changes in the lipid profile produced by aerobic exercise, training-induced lipid profile changes in atherosclerosis-prone type 1 diabetes mellitus (DM) have not heretofore been adequately addressed.

We assessed the effect of a 12- to 16-wk aerobic exercise program on cardiorespiratory fitness and the lipid profile in young men with type 1 DM. Generally active men aged 20-40 yr with type 1 DM (N = 56) were randomized into training (N = 28) and control (untrained, N = 28) groups after baseline measurements. Training consisted of 30-60 min moderate-intensity running 3-5 times a week for 12-16 wk.

For the 42 men finishing the study, peak oxygen consumption (VO2 peak) increased significantly only in the trained group. Total and low-density lipoprotein (LDL) cholesterol and apolipoprotein (apo) B decreased and the high-density lipoprotein (HDL)/apo A-I ratio increased in the trained group. HDL and apo A-I increased in both groups. The exercise program brought about improvements in the HDL/LDL and apo A-I/apo B ratios and apo B and triglyceride levels when comparing the relative (%) changes in the trained versus control group. In the trained group, men with HDL/LDL ratios below the group median at baseline showed even more favorable changes in their lipid profile than those with higher initial HDL/LDL ratios. Body mass index, percent body fat and hemoglobin A1c did not change during the training period in either group.

Endurance training improved the lipid profile in already physically active type 1 diabetic men, independently of effects on body composition or glycemic control. The most favorable changes were in patients with low baseline HDL/LDL ratios, likely the group with the greatest benefit to be gained by such changes.