Role of vitamin D in energy and bone metabolism in postmenopausal women with type 2 diabetes mellitus: A 6‐month follow‐up evaluation

AIMS/INTRODUCTION: Resting energy expenditure was associated with a serum bone turnover marker in postmenopausal women with type 2 diabetes (T2DMPW) in the present cross‐sectional study. To clarify the fundamental pathological factor for the correlation of bone metabolism and basal metabolism in type 2 diabetes, a 6‐month prospective follow‐up study was carried out with supplementation of vitamin D. MATERIALS AND METHODS: A total of 44 T2DMPW were enrolled. The following factors were evaluated at the beginning and the end of the summer: procollagen type 1 N‐terminal propeptide, carboxy‐terminal collagen crosslinks‐1, intact parathyroid hormone and 25‐hydroxyvitamin D (25[OH]D), as well as diabetic complications, body composition, respiratory quotient and resting energy expenditure. A total of 23 patients with low 25(OH)D levels (˂20 ng/mL) were instructed to increase vitamin D levels by lifestyle change. Among them, 15 patients with osteoporosis were also administered alfacalcidol. RESULTS: Serum 25(OH)D increased in 25 patients and decreased in 19 patients. Patients who did not receive the study intervention at the start tended to have a decreased 2525(OH)D level; therefore, the average 25(OH)D level of all patients was not changed. Changes in resting energy expenditure were positively correlated with those of procollagen type 1 N‐terminal propeptide/carboxy‐terminal collagen crosslinks‐1. Changes in the respiratory quotient correlated with the mean glycated hemoglobin levels; procollagen type 1 N‐terminal propeptide levels positively correlated with serum 25(OH)D after the intervention. These correlations were prominent in patients with increased 25(OH)D and those with alfacalcidol supplementation. CONCLUSIONS: Restoration of vitamin D level might be a prerequisite for a normal correlation between bone and basal metabolism in T2DMPW. Lifestyle intervention for retention of vitamin D level is important even in summer, in T2DMPW.