Background: Near-infrared time-resolved spectroscopy is a non-invasive method that facilitates analysis of human brown adipose tissue (BAT) density. We measured BAT density in middle-aged patients who had type 2 diabetes by this method and examined the relationship using clinical parameters.
Methods: We studied 33 Japanese middle-aged diabetic patients (30 male and 3 female, age 53.8±10.1 years, BMI 25.4±4.5, and HbA1c 7.2±1.1%). Tissue hemoglobin concentration (tHb) of the supraclavicular region was measured using near-infrared time-resolved spectroscopy, and normalized by subcutaneous fat thickness at the measurement sites.
Results: The average tHb concentration was 51.1±17.7 μM and lower than 77.8 μM—the value equivalent to the detection threshold of BAT by standard FDG-PET in young adults. Univariate regression analysis showed that the tHb of the supraclavicular region was inversely correlated with BMI (r = −0.55, p=0.0009), but the tHb of the deltoid region was not (r = 0.04, p = 0.31). Other parameters showing significant correlations with BAT mass included systolic blood pressure (r = −0.47, p = 0.01) and insulin treatment (r=0.45, p=0.01). Multivariate regression analysis suggested that BMI (β=−0.42, p=0.005), systolic blood pressure (β=−0.29, p=0.042), and insulin treatment (β=0.34, p=0.015) independently account for BAT density.
Conclusion: Our findings suggest that BAT density in middle-aged diabetic patients may relate to obesity more closely than previously thought.
H. Waki: Research Support; Self; MSD K.K., Novartis Pharma K.K., Boehringer Ingelheim Pharmaceuticals, Inc., Sanofi K.K., Ono Pharmaceutical Co., Ltd., Kyowa Hakko Kirin Co., Ltd., Takeda PHarmaceutical Co., Ltd.. N. Watanabe: None. S. Fuse: None. Y. Kurosawa: None. T. Yamauchi: Research Support; Self; Novo Nordisk Inc., Daiichi Sankyo Company, Limited, Sanofi, Takeda, Tanabe-Mitsubishi. R. Kime: None. T. Hamaoka: None. T. Kadowaki: Consultant; Self; Novo Nordisk A/S, AstraZeneca, Merck Sharp & Dohme Corp.. Research Support; Self; Kissei Pharmaceutical Co., Ltd., Taisho Pharmaceutical Co., Ltd., Sanofi, Kyowa Hakko Kirin Co., Ltd., Novo Nordisk A/S, Astellas Pharma, Daiichi Sankyo Company, Limited, Takeda, Mitsubishi Tanabe Pharma Corporation, Ono Pharmaceutical Co., Ltd., Merck Sharp & Dohme Corp., Nippon Boehringer Ingelheim Co. Ltd.. Speaker's Bureau; Self; Astellas Pharma, AstraZeneca, Merck Sharp & Dohme Corp., Ono Pharmaceutical Co., Ltd., Takeda, Eli Lilly and Company, Nippon Boehringer Ingelheim Co. Ltd., Novo Nordisk A/S.