A Study of Vitamin D Insufficiency in Postmenopausal Type 2 Diabetic Women

AbstractBackgroundType 2 diabetic elderly women are at increased risk for osteoporotic fractures. Low levels of vitamin D increases this risk. We aimed to measure levels of 25 hydroxy vitamin D (25 OH-D) in these patients to help assess the level of risk.Patients and MethodsIn this cross sectional case-control study, the serum concentrations of 25 OH-D were measured by high performance liquid chromatography (HPLC) in 60 ambulatory, postmenopausal, type 2 diabetic female patients under oral anti-diabetic treatment. Thirty control females were comparable for weight, age and years since menopause. Calcium and Vitamin D intake (obtained by 24 hour dietary recall), sun exposure, parathyroid hormone (PTH), serum calcium, phosphorus and alkaline phosphatase were also assessed.ResultsThe prevalence of 25 OH-D insufficiency was significantly higher in diabetic patients than in control subjects (38.3% vs. 20%, p<0.01). About 13% of diabetics with vitamin D insufficiency had high PTH levels. While most of the control group with 25 OH-D insufficiency had elevated PTH levels. Out of 66 diabetic women, only 11.7% had adequate vitamin D intake and 30% had adequate calcium intake. Similarly, in non-diabetic women, only 13.3% had adequate vitamin D intake and 26.7% had adequate calcium intake. However, a highly significantly percentage of diabetic women (43.4%) with inadequate vitamin D intake develop vitamin D insufficiency compared with non-diabetic women (23.1%) (p<0.001). Diabetic patients with 25 OH-D insufficiency tend to be older, with higher BMI, and HBA1C (P<0.01, <0.01, <0.001 respectively).ConclusionWe documented increased risk of vitamin D insufficiency in type 2 diabetic postmenopausal women in the face of inadequate dietary vitamin D and low sun exposure. This finding might partially explain the increased risk for osteoporosis among this group and warrants consideration of dietary vitamin D supplementation