Relationship between bone metabolism markers, bone mineral density and insulinresistance in healthy and diabetic postmenopausal women
G. Perez Lopez1, A. Becerra Fernandez2 & M. Menacho Roman2
Introduction: Some metabolic diseases, including type 1 (T1DM) and type 2 (T2DM) diabetes mellitus have an influence on bone homeostasis. These facts are of great socio-medical impact, since currently the DM2 and osteoporosis are considered public health problems.
Objectives: (1) Determine the relationship between markers of bone metabolism and insulin resistance in postmenopausal women with and without T2DM.
(2) Compare the bone mineral density between the two groups.
Methodology: Prospective and casecontrol study. Postmenopausal women attending in outpatient Endocrinology from January to December 2010 were included consecutively. T2DM patients treated with oral hypoglycemic agents (except glitazones) and patients with other diseases that not interfere with bone metabolism were included. The study included 18 women with diabetes and 58 without diabetes. The average age of the sample was 54.6±1.8 years. In the diabetic group the duration of diabetes was 4.6±2.4 years. Measurements included anthropometric (BMI), biochemical (insulin, C-peptide, HOMA-IR, P1NP, β-crosslap, osteocalcin, 25-OH-vitamin D, PTH, calcium, phosphorus, renal function) and radiographic (bone densitometry: T-score) variables.
Results: BMI was similar between groups. The HOMA-IR was 7.9±0.6 in the DM2 group and 3.0±0.7 in the control group (P<0.05). Osteocalcin was lower in diabetics (14.6±3.8 ng/ml, P<0.01) than in healthy patients. The same trend was observed at concentrations of P1NP. In densitometry, 20% of diabetics had osteoporosis and 40% osteopenia. In the healthy group, 35% had osteoporosis and 52% osteopenia. In the diabetic group HOMA-IR was associated directly with BMD (r=0.568, P<0.05) and HOMA-IR inversely with osteocalcin (r=−0.624, P<0.05). Also in the group of healthy patients with P1NP was related directly with BMD and HOMA-IR inversely with BMD.
Conclusions: Insulin resistance is a predictor of BMD. Osteocalcin is related to insulin resistance, as it is clearly diminished in diabetics. P1NP concentration is related directly with BMD in the healthy group. Osteoporosis and osteopenia were higher in the healthy patients than in diabetic patients. More studies are needed to explain the fact why despite having higher BMD, diabetics are more likely to fracture than healthy women.
Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.
Funding: This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector.