Brown adipose tissue (BAT) is present in a significant number of adult humans and has been postulated to exert beneficial metabolic effects. Lean, nondiabetic patients undergoing clinical PET/CT imaging are more likely to exhibit incidental BAT activation. The aim of this study was to assess metabolic changes associated with the cold activation of BAT and to compare baseline blood metabolites in participants with varying amounts of active BAT. Methods: Serum blood samples were collected from healthy adult volunteers (body mass index, 18.0–25.0, and age ≤ 35 y) before and after 2 h of exposure to cold. ¹⁸F-FDG PET/CT imaging was performed immediately after cold exposure. Activated BAT was segmented, and fasting glucose, insulin, lipid, and other blood metabolite levels were correlated with volume and intensity of active BAT. Using a median cutoff, subjects were classified as high-BAT (BAT_high) or low-BAT (BAT_low). Results: A higher volume of activated BAT was associated with significantly higher precooling glucose and insulin levels (P < 0.001 for each). Precooling thyroid-stimulating hormone and triglyceride levels were significantly higher in the BAT_high than the BAT_low group (P = 0.002 and P < 0.001, respectively). Triglyceride levels tended to increase over the cooling period in both BAT groups but increased significantly more in the BAT_high group (15.7 ± 13.2 mg/dL; P < 0.001) than in the BAT_low group (4.5 ± 12.2 mg/dL; P = 0.061). Conclusion: These findings may indicate that BAT is recruited to counteract incipient “preprediabetic” states, potentially serving as a first-line protective mechanism against very early metabolic or hormonal variations.

棕色脂肪组织 (BAT) 存在于大量成年人中，并被假定具有有益的代谢作用。接受临床 PET/CT 成像的瘦、非糖尿病患者更有可能表现出偶然的 BAT 激活。本研究的目的是评估与 BAT 冷激活相关的代谢变化，并比较具有不同数量活性 BAT 的参与者的基线血液代谢物。方法：从健康成年志愿者（体重指数，18.0-25.0，年龄≤35岁）在暴露于寒冷2小时之前和之后采集血清血样。¹⁸冷暴露后立即进行 F-FDG PET/CT 成像。活化 BAT 被分段，空腹血糖、胰岛素、脂质和其他血液代谢物水平与活性 BAT 的体积和强度相关。使用中值截止值，受试者被分类为高 BAT（BAT_高）或低 BAT（BAT_低）。结果：较高体积的活化 BAT 与显着较高的预冷葡萄糖和胰岛素水平相关（每个P < 0.001）。_BAT高组的预冷促甲状腺激素和甘油三酯水平显着高于BAT_低组（P = 0.002和P< 0.001，分别）。在两个 BAT 组的冷却期间，甘油三酯水平趋于增加，但 BAT_高组（15.7 ± 13.2 mg/dL；P < 0.001）显着高于 BAT_低组（4.5 ± 12.2 mg/dL；P = 0.061)。结论：这些发现可能表明，BAT 被招募来对抗早期的“前驱糖尿病”状态，可能作为针对极早期代谢或激素变化的一线保护机制。