Brown Fat Can Protect Against Diabetes and Obesity

Brown adipose tissue, a.k.a. brown fat, may play a role in glucose metabolism, and thus influence the risk of developing diabetes.

Brown adipose tissue may have therapeutic potential and offer protection against diabetes and obesity. Unlike white adipose tissue that increases metabolic risk, brown fat burns energy for thermogenesis.  Previous studies have investigated the clinical significance of increasing brown adipocytes, but research involving glucose metabolism and brown adipose tissue is limited in humans. It is known that human brown adipose tissue has insulin sensitivity comparable to skeletal muscle. Previous studies have confirmed that adults have functional brown adipose tissue that responds to cold stimulation with the capacity to reduce obesity, but studies on this are limited in children. The aim of this study was to investigate the associations of glucose metabolism and brown adipose tissue in children and adolescents.

This study was based on data from the Beta-Cell Function in Juvenile Diabetes and Obesity European cohort study. After exclusions, 143 participants aged 10-20 years were included in the study. Patients completed a glucose tolerance test and this data was used to evaluate four parameters. They include concentration glucose at 120 minutes, the Matsuda index to calculate insulin sensitivity, HOMA‐IR, and the oral disposition index. 

Patients with 7.8 mmol/l ≤2h glucose < 11.1 mmol/l were categorized as having prediabetes and patients with 2h glucose≥11.1 mmol/l were categorized as having diabetes. Magnetic resonance imaging was used to estimate brown adipose tissue with suspected brown adipose tissue fat fraction and the joint effective transverse relaxation time for the water and fat signals.  These images were also used to calculate back subcutaneous adipose tissue fat fraction. Simple and multiple linear regression analysis was used to compare the associations between brown adipose tissue estimates, age, adiposity, and glucose metabolism. Adiposity was estimated with patient body mass index, waist to height ratio, and adipose tissue volumes. This study chose a less invasive method for assessing glucose metabolism and although it was more convenient for the patient, it was not considered the gold standard and is a study limitation. Another limiting factor is that dedicated standards for magnetic resonance imaging for brown adipose tissue measurements do not exist.

This data showed that brown adipose tissue plays a significant role in glucose metabolism and this may influence a person’s risk of developing diabetes. Of the 143 participants, 28 had pre-diabetes and 1 had diabetes. Brown adipose tissue fat fraction and the joint effective transverse relaxation time for the water and fat signals are associated with adiposity even after adjustments for possible confounders were made. Brown adipose tissue fat fraction was directly associated with a patient’s 2-hour glucose level and their insulin sensitivity index. More research is required to understand why brown adipose tissue is correlated to 2-hour glucose level and insulin sensitivity. Once this mechanism is understood and a technique or drug is approved to increase brown adipose tissue thermogenesis, this data can be used to prevent obesity and diabetes.

Practice Pearls:

• This study shows that brown adipose tissue plays a role in glucose metabolism, but the mechanism is not understood.
•  Human brown adipose tissue has insulin sensitivity comparable to skeletal muscle.
• Brown adipose tissue fat fraction and the joint effective transverse relaxation time for the water and fat signals are associated with adiposity.

 Lundström, E., Ljungberg, J., Andersson, J., Manell, H., Strand, R., Forslund, A., . . . Kullberg, J. (2019, July 09). Brown adipose tissue estimated with the magnetic resonance imaging fat fraction is associated with glucose metabolism in adolescents – Lundström – – Pediatric Obesity – Wiley Online Library. Retrieved from https://onlinelibrary.wiley.com/doi/full/10.1111/ijpo.12531

Cypess, A. M., & Kahn, C. R. (2010). Brown fat as a therapy for obesity and diabetes. Current Opinion in Endocrinology, Diabetes and Obesity, 17(2), 143-149. doi:10.1097/med.0b013e328337a81f

Kassey James, Pharm.D.Candidate, LECOM School of Pharmacy