Emerging Aspects of the Body Composition, Bone Marrow Adipose Tissue and Skeletal Phenotypes in Type 1 Diabetes Mellitus.

Anthropomorphic measures among type 1 diabetic patients are changing as the obesity epidemic continues. Excess fat mass may impact bone density and ultimately fracture risk. We studied the interaction between bone and adipose tissue in type 1 diabetes subjects submitted to two different clinical managements: (I) conventional insulin therapy or (II) autologous nonmyeloablative hematopoietic stem-cell transplantation (AHST). The study comprised 3 groups matched by age, gender, height and weight: control (C = 24), type 1 diabetes (T1D = 23) and type 1 diabetes treated with AHST (T1D-AHST = 9). Bone mineral density (BMD) and trabecular bone score (TBS) were assessed by dual X-ray absorptiometry (DXA). 1H Magnetic resonance spectroscopy was used to assess bone marrow adipose tissue (BMAT) in the L3 vertebra, and abdominal magnetic resonance imaging was used to assess intrahepatic lipids (IHL), visceral (VAT) and subcutaneous adipose tissue (SAT). Individuals conventionally treated for T1D were more likely to be overweight (C = 23.8 ± 3.7; T1D = 25.3 ± 3.4; T1D-AHST = 22.5 ± 2.2 Kg/m2; p > 0.05), but there was no excessive lipid accumulation in VAT or liver. Areal BMD of the three groups were similar at all sites; lumbar spine TBS (L3) was lower in type 1 diabetes (p < 0.05). Neither SAT nor VAT had any association with bone parameters. Bone marrow adipose tissue (BMAT) lipid profiles were similar among groups. BMAT saturated lipids were associated with cholesterol, whereas unsaturated lipids had an association with IGF1. Overweight and normal weight subjects with type 1 diabetes have normal areal bone density, but lower trabecular bone scores. Adipose distribution is normal and BMAT volume is similar to controls, irrespective of clinical treatment.

Marrow Fat Quality Differences by Sex in Healthy Adults.

Several studies have demonstrated the relationship between bone marrow adiposity (BMAT) and bone mass. 1H magnetic resonance spectroscopy is a noninvasive technique able to assess both BMAT quantity and quality. The aim of our study was to perform quantitative and qualitative analyses of BMAT and to investigate its association with bone mineral density (BMD) in healthy nonobese volunteers. Fifty-one healthy volunteers, 21 men and 30 women, underwent 1.5 T 1H magnetic resonance spectroscopy of the lumbar spine. BMD was determined by dual-energy X-ray absorptiometry of the lumbar spine. Correlation analysis was performed to evaluate association among lipids fractions, BMD, and age. The female and male volunteers had similar body mass index and BMD (p > 0.05). Our data demonstrated an inverse correlation of BMD and BMAT with age, with a stronger correlation of saturated lipids (r = 0.701; p < 0.0001) compared with unsaturated lipids (UL) (r = 0.278; p = 0.004). Importantly, female subjects had the highest amount of UL (confidence interval: 0.685%-1.722%; p < 0.001). Our study reports that men and women with similar BMD and body mass index have striking differences in bone marrow lipids composition, namely women have higher UL than men. In addition, we believe that our study brings new insights to the complex network involving BMAT and other factors that influence bone integrity.

The Relationship of Fat Distribution and Insulin Resistance with Lumbar Spine Bone Mass in Women.

Bone marrow harbors a significant amount of body adipose tissue (BMAT). While BMAT might be a source of energy for bone modeling and remodeling, its increment can also represent impairment of osteoblast differentiation. The relationship between BMAT, bone mass and insulin sensitivity is only partially understood and seems to depend on the circumstances. The present study was designed to assess the association of BMAT with bone mineral density in the lumbar spine as well as with visceral adipose tissue, intrahepatic lipids, HOMA-IR, and serum levels of insulin and glucose. This cross-sectional clinical investigation included 31 non-diabetic women, but 11 had a pre-diabetes status. Dual X-ray energy absorptiometry was used to measure bone mineral density and magnetic resonance imaging was used to assess fat deposition in BMAT, visceral adipose tissue and liver. Our results suggest that in non-diabetic, there is an inverse relationship between bone mineral density in lumbar spine and BMAT and a trend persists after adjustment for weight, age, BMI and height. While there is a positive association between visceral adipose tissue and intrahepatic lipids with serum insulin levels, there is no association between BMAT and serum levels of insulin. Conversely, a positive relationship was observed between BMAT and serum glucose levels, whereas this association was not observed with other fat deposits. These relationships did not apply after adjustment for body weight, BMI, height and age. The present study shows that in a group of predominantly non-obese women the association between insulin resistance and BMAT is not an early event, as occurs with visceral adipose tissue and intrahepatic lipids. On the other hand, BMAT has a negative relationship with bone mineral density. Taken together, the results support the view that bone has a complex and non-linear relationship with energy metabolism.