Preventing Diabetic Osteoporosis With Exercise

The study addresses the problem that postmenopausal women with type 2 diabetes have a higher incidence of bone breaks despite their often normal bone mineral density (BMD).

The investigators pursued two hypotheses, that:

• 40-minute bout of downhill exercise will increase the CICP/CTX osteogenic index to a greater extent than the same amount of uphill exercise; and
• Performing exercise one hour after the meals will be more osteogenic than exercise before the meals.

Subjects were 15 postmenopausal women with type 2 diabetes, age 57.7 years, BMI 27.2 kg/m2 who were randomly assigned to two out of 5 trials:

Uphill exercise before the meals (UBM), Uphill exercise after the meals (UAM), Downhill exercise before the meals (DBM), Downhill exercise after the meals (DAM), and Sedentary, no-exercise, trial (SED). All subjects signed an informed consent approved by the University of Michigan Medical School Institutional Review Board. Subjects had their BMD measured with DXA at the outset.

Weight-maintenance meals contained 50% carbohydrate, 15% protein, and 25% fat and were provided at 10 h and 17 h. Exercise (40 minutes at 50% of maximal effort) on either uphill (+6o slope) or downhill treadmill (-6o slope) was performed either before the two meals, at 9 h and 16 h, respectively, or after the meals. at 11 h and 18 h, respectively.

Blood was drawn through an intravenous catheter from ante-cubital vein at hourly intervals between 8 and 20 h with two additional blood draws at 0 h and 6 h the next morning. Blood was treated with protease inhibitors, and plasma, frozen at -80o C, was used to measure bone markers, CICP, CTX, osteocalcin , and bone-specific alkaline phosphatase using Millipore chemoluminescen reagents, glucose by glucose oxidase, and hormones insulin, cortisol, parathyroid hormone (PTH) , and growth hormone (GH) by radio-immunoassays..

Mixed-model ANOVA was used for analysis of outcome measures where the trial procedures served as fixed variable and individual subjects as intercept variables.

Inclusion criteria

postmenopausal type-2 diabetes melllitus age between 50 and 65 exercise less than 20 minutes three times a week

Exclusion criteria

metabolic disease other than type-2 diabetes and hormonally-corrected hypothyroidism musculo-skeletal disability that would preclude exercise smoker do not meet inclusion criteria