Relationships among the metabolic syndrome, bone mineral density, bone turnover markers, and hyperglycemia.

BACKGROUND: This study investigated the possible effects of metabolic syndrome on bone mineral density (BMD) and bone turnover markers in Turkish postmenopausal women.

METHOD: This prospective case-control study included a total of 230 postmenopausal women, between 45 and 65 years old, including 63 with metabolic syndrome and 167 without metabolic syndrome on the basis of the International Diabetes Federation criteria. The height, weight, body mass index (BMI), waist circumference, hip circumference, and waist-to-hip ratio of each subject were measured. Fasting and nonfasting blood glucose, triglycerides, total cholesterol, low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), parathyroid hormone (PTH), thyroid-stimulating hormone (TSH), calcium, phosphorus, glycated hemoglobin (HbA1c), bone-specific alkaline phosphatase (ALP), 25-hydroxyvitamin D3 [25(OH) D], osteocalcin, and the β-isomerized form carboxy-terminal telopeptide of type I collagen (β-CTx) were measured. Bone mineral densities in the lumbar spine and femoral neck were measured by dual energy X-ray absorptiometry.

RESULTS: The mean age was 58.49±5.7 years in metabolic syndrome patients and 56.13±5.0 years in patients without metabolic syndrome. There was a statistically significant difference in the age of the patients. The mean BMI was 33.96±5.3 and 30.867±3.8 kg/m(2) in metabolic syndrome patients and patients without metabolic syndrome, respectively, indicating a statistically significant difference. Serum calcium, osteocalcin, and β-CTx were statistically significantly lower in metabolic syndrome patients. There was no significant difference in the levels of phosphorus, 25-hydroxyvitamin D3, and bone-specific ALP, TSH, and PTH among the patients with metabolic syndrome and without metabolic syndrome. The statistical analysis, after adjusting for age and BMI, revealed no significant difference between the two groups in terms of lumbar and femoral BMD. When the patients in the metabolic syndrome group were split into two groups on the basis of those with a T score -2.5 or less and those with a normal score, a statistically significant difference was identified between the two groups in terms of the fasting blood glucose (FBG) and HbA1c values (P<0.05). Furthermore, a negative correlation was identified between the lumbar T score and the FBG and HbA1c values (P<0.05).

CONCLUSION: After adjusting for age and BMI in a comparison of BMD between postmenopausal women with and without metabolic syndrome, it was revealed that metabolic syndrome has no positive or negative effect on BMD. In contrast, a negative correlation was identified between FBG and HbA1c levels and lumbar BMD, suggesting that poor glycemic control may have a negative effect on lumbar BMD in this group of patients.