Objective: The aim of this study was to assess the incidence of vitamin D deficiency in Japanese postmenopausal women with type 2 diabetes mellitus.
Methods: Serum 25-hydroxyvitamin D [25(OH)D], intact-parathyroid hormone (PTH), and various bone markers were measured. The primary outcome was the serum level of 25(OH)D.
Patients: This study included postmenopausal women with type 2 diabetes mellitus.
Results: The study patients included 170 women with a mean 25(OH)D of 20.0 ng/mL. With regard to the serum level of 25(OH)D, the patients were defined as normal (≥30 ng/mL, 8.2% of the patients) and abnormal (<30 ng/mL, 91.8% of the patients, vitamin D deficiency). The latter group was subdivided into severe deficiency (<10 ng/mL, 2.9% of the patients), deficiency (10-19 ng/mL, 47.1% of the patients), and insufficiency (20-29 ng/mL, 41.8% of the patients). There was a significant negative correlation between the serum 25(OH)D level with type I collagen cross-linked N-telopeptides (NTX) and intact-PTH, but not between 25(OH)D and the bone quality markers. There was a significant positive correlation between 25(OH)D and the radial bone mineral density, but not between 25(OH)D and the bone mineral density on the lumbar vertebrae and femur. A multivariate analysis identified NTX as the only significant determinant of 25(OH)D. The cutoff value of 25(OH)D was 18.5 ng/mL based on a Receiver Operatorating Characteristic analysis.
Conclusion: Our results showed an alarmingly high incidence of vitamin D deficiency in Japanese women with type 2 diabetes mellitus, with a risk of radial bone osteoporosis, particularly in those patients with a serum 25(OH)D level of <18.5 ng/mL.