Featured Investigators

Tiffany Kim, MD - Bone marrow fat and skeletal health in type 2 diabetes

Figure 1: Greater bone marrow adipose tissue (BMAT) levels are seen in osteoporosis and other skeletal disorders. Mechanisms for the negative effects of BMAT on bone include: enhanced adipogenesis at the expense of osteoblastogenesis, a direct negative effect of adipocytes on osteoblasts, and adipocyte promotion of osteoclastogenesis.

In individuals with type 2 diabetes (T2D), fracture risk is increased, in part due to intrinsic skeletal disease. Among the multifactorial etiologies of skeletal fragility in T2D, bone marrow adipose tissue (BMAT) is a metabolic fat depot that may also play a negative role in skeletal disease and specifically in T2D.  Whether enhanced glycemic control affects skeletal outcomes through pathways such as BMAT is unknown.
Our group is currently investigating the effects of improved glycemic control on BMAT and skeletal outcomes in a longitudinal, prospective study of older Veterans with type 2 diabetes at the San Francisco VA. To date, 48 participants have enrolled and are actively working with their clinicians to improve the medical management of their diabetes.  Eighty-eight percent of participants were men, the average age was 66 years, and the mean BMI was 32 k/m2.  In our interim analyses, we observed a notable reduction in mean hemoglobin A1c levels from 9.4% to 7.9%, indicating a clinically significant improvement in glycemic control.  We did not observe a statistically significant change in total vertebral BMAT content, assessed by magnetic resonance spectroscopy.  However, mean femoral neck BMD declined by -1.4% ± 2.9% (p=0.006) and there was a negative correlation between changes in femoral neck BMD and total vertebral BMAT content (r=-0.45, p=0.01).  Meaning participants who had greater declines in femoral neck BMD generally had increases in vertebral BMAT. 
As we continue to collect and analyze data, we are excited to better understand underlying mechanisms that drive the relationship between glycemic control, BMAT, and skeletal health in people with T2D.  These insights hold the potential to inform more targeted and effective clinical interventions for managing diabetic bone disease and mitigating the risk of fractures in this vulnerable population.

Tiffany Kim, MD

Assistant Professor of Medicine, Division of Endocrinology and Metabolism, UCSF & Staff Physician, San Francisco VA Health Care System


Research interests: osteoporosis, bone metabolism


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