Brown fat detected by FDG PET/CT is protective against elevated fasting blood glucose in obese patients

2715 Objectives It has been demonstrated that brown fat (BF) is protective against features of metabolic syndrome. Two important factors used to diagnose metabolic syndrome are body mass index (BMI) >30, and fasting blood sugar (FBS) >100 mg/dl. Also, studies have shown a higher female prevalence of BF. The purpose of this study is to determine if BF is protective against elevated FBS in obese patients and if gender plays a role. Methods Retrospective analysis of 4,458 PET/CT studies from one institution between 2011-2013 identified 37 adult oncology patients (>21 years of age) with FDG BF uptake. The control cohort consisted of 74 (2matched control cases for each BF case) adult oncology patients without FDG BF uptake, matched for BMI, gender, and season. Records were reviewed to determine BMI and FBS on the date of the PET/CT study. The average FBS of the 26 total obese patients (BMI >30) (9 from the BF cohort and 17 from the control) were compared by t-test analysis. Control vs. BF FBS data was then analyzed by gender, BMI, and FBS (≥100mg/dl) with a Fisher’s exact test. Results The 9 obese BF patients had significantly lower FBS (92.3+/-8.7mg/dl) compared to 17 obese control patients (133.2+/-36.1mg/dl)(P=0.00028). A significantly lower proportion of obese BF patients had FBS ≥100mg/dl compared to control patients [33% (3/9) vs. 82% (14/17), P=0.03]. In this study, gender had no significant effect on FBS. Conclusions Obesity and elevated FBS are important risk factors for metabolic syndrome. This data shows that BF may be protective against an elevated FBS in obese patients. Although previous studies showed a higher prevalence of females with BF, there was no significant gender difference in FBS among obese patients in this study.