Effect of type 2 diabetes mellitus on treatment outcomes of patients with postmenopausal osteoporosis: a retrospective study

Effect of a single dose of zoledronic acid on bone mineral density and trabecular bone score in Indian postmenopausal osteoporotic women with and without type 2 diabetes mellitus - A prospective cohort pilot study

PURPOSE

The objectives were to study the effect of a single dose of intravenous (IV) zoledronic acid (ZA) on changes in bone mineral density (BMD) (lumbar spine (LS), hip, & distal forearm), trabecular bone score (TBS) and bone turnover markers (BTMs) in postmenopausal osteoporotic women with and without diabetes over 12 months.

METHODS

Patients were divided into two groups: type 2 diabetes mellitus (T2DM) (n = 40) and non-DM (n = 40). Both groups received a single dose of 4 mg IV ZA at baseline. The BMD with TBS and BTMs (β-CTX, sclerostin, P1NP) were measured at baseline, six months, and 12 months.

RESULTS

At baseline, BMD in all three sites was similar in both groups. T2DM patients were older and had lower BTMs than non-DM patients. The mean increase in LS-BMD (gram/cm2) at 12 months in T2DM and the non-DM group was 3.6 ± 4.7% and 6.2 ± 4.7 %, respectively (P = 0.01). However, the age adjusted mean difference in LS BMD increment between two groups at one year was - 2.86 % (-5.02% to -0.69%), P = 0.01. There was a comparable change in BMD at other two sites, BTMs, and TBS in both the groups over one year follow-up.

CONCLUSION

The gain in the LS-BMD was significantly lower in T2DM group compared to non-DM subjects over 12 months after a single IV infusion of 4 mg ZA. The explanation for this could be low bone turnover in diabetes subjects at baseline.

Nmp4, a Regulator of Induced Osteoanabolism, Also Influences Insulin Secretion and Sensitivity

A bidirectional and complex relationship exists between bone and glycemia. Persons with type 2 diabetes (T2D) are at risk for bone loss and fracture, however, heightened osteoanabolism may ameliorate T2D-induced deficits in glycemia as bone-forming osteoblasts contribute to energy metabolism via increased glucose uptake and cellular glycolysis. Mice globally lacking nuclear matrix protein 4 (Nmp4), a transcription factor expressed in all tissues and conserved between humans and rodents, are healthy and exhibit enhanced bone formation in response to anabolic osteoporosis therapies. To test whether loss of Nmp4 similarly impacted bone deficits caused by diet-induced obesity, male wild-type and Nmp4-/- mice (8 weeks) were fed either low-fat diet or high-fat diet (HFD) for 12 weeks. Endpoint parameters included bone architecture, structural and estimated tissue-level mechanical properties, body weight/composition, glucose-stimulated insulin secretion, glucose tolerance, insulin tolerance, and metabolic cage analysis. HFD diminished bone architecture and ultimate force and stiffness equally in both genotypes. Unexpectedly, the Nmp4-/- mice exhibited deficits in pancreatic β-cell function and were modestly glucose intolerant under normal diet conditions. Despite the β-cell deficits, the Nmp4-/- mice were less sensitive to HFD-induced weight gain, increases in % fat mass, and decreases in glucose tolerance and insulin sensitivity. We conclude that Nmp4 supports pancreatic β-cell function but suppresses peripheral glucose utilization, perhaps contributing to its suppression of induced skeletal anabolism. Selective disruption of Nmp4 in peripheral tissues may provide a strategy for improving both induced osteoanabolism and energy metabolism in comorbid patients.

Distinct Effects of a High Fat Diet on Bone in Skeletally Mature and Developing Male C57BL/6J Mice

Increased risks of skeletal fractures are common in patients with impaired glucose handling and type 2 diabetes mellitus (T2DM). The pathogenesis of skeletal fragility in these patients remains ill-defined as patients present with normal to high bone mineral density. With increasing cases of glucose intolerance and T2DM it is imperative that we develop an accurate rodent model for further investigation. We hypothesized that a high fat diet (60%) administered to developing male C57BL/6J mice that had not reached skeletal maturity would over represent bone microarchitectural implications, and that skeletally mature mice would better represent adult-onset glucose intolerance and the pre-diabetes phenotype. Two groups of developing (8 week) and mature (12 week) male C57BL/6J mice were placed onto either a normal chow (NC) or high fat diet (HFD) for 10 weeks. Oral glucose tolerance tests were performed throughout the study period. Long bones were excised and analysed for ex vivo biomechanical testing, micro-computed tomography, 2D histomorphometry and gene/protein expression analyses. The HFD increased fasting blood glucose and significantly reduced glucose tolerance in both age groups by week 7 of the diets. The HFD reduced biomechanical strength, both cortical and trabecular indices in the developing mice, but only affected cortical outcomes in the mature mice. Similar results were reflected in the 2D histomorphometry. Tibial gene expression revealed decreased bone formation in the HFD mice of both age groups, i.e., decreased osteocalcin expression and increased sclerostin RNA expression. In the mature mice only, while the HFD led to a non-significant reduction in runt-related transcription factor 2 (Runx2) RNA expression, this decrease became significant at the protein level in the femora. Our mature HFD mouse model more accurately represents late-onset impaired glucose tolerance/pre-T2DM cases in humans and can be used to uncover potential insights into reduced bone formation as a mechanism of skeletal fragility in these patients.

Effect of Primary Hypertension on Treatment Outcomes of Patients with Postmenopausal Osteoporosis: A 5 Year Follow Up Retrospective Study

AIM

To investigate the efficacy of primary hypertension (HTN) on the treatment prognosis of patients with postmenopausal osteoporosis (PMOP).

METHODS

45 patients who were diagnosed as PMOP with lumbar and/or femur neck bone mineral density screening (BMD) but have no history of PMOP treatment including calcium and vitamin D, have comorbid primary HTN and treated with a vasodilator antihypertensive drug at least a year were included to the study. Control group was constituted with 44 patients with PMOP at same age but have no comorbidity. Demographic features including age, height, weight, occupation, educational level menarche and menopause age, clothing style, daily intake of calcium, smoking and/or alcohol consumption, daily physical activity level, personal history of fragility fracture or in mother and duration of primary HTN diagnosis were recorded. Biochemical parameters were also recorded. Patients were treated with bisphosphonate, calcium and vitamin D and same parameters were evaluated at the end of first and fifth year.

RESULTS

Demographic and disease characteristics were not different between groups before treatment (p > 0.05). In group analysis, there was significant improvement in lumbar and femur neck T scores of PMOP + HT and PMOP groups after 1 and 5 years of treatment compared to baseline (p < 0.05) Lumbar and femur neck T score variations between the baseline, first and fifth years of treatment were not significantly different in PMOP + HT and PMOP groups (p < 0.05).

CONCLUSIONS

Although the results vary between populations, primary HTN does not have an impact on the prognosis of PMOP treatment in Turkish population.