Figure 3.

Metabolic consequences of BAT acclimatization at 24°C. A and B: Comparison of postprandial glucose and insulin excursions after a mixed meal at 1300 h before and after cold acclimatization, respectively, measured at 24°C. Unlike measurements at 19°C (Fig. 2A and B), no significant changes were observed in glucose or insulin excursions. Accordingly, adipocyte insulin resistance (IR) (C) and Matsuda index (an indicator of insulin sensitivity) (D) were unchanged. Circulating adiponectin increased (E), while leptin decreased (F), identical to measurements observed at 19°C (Fig. 2E and F). Cold acclimatization–induced changes (months 1 and 2) in circulating adiponectin (G) and leptin levels (H) correlated negatively with changes in BAT activity. In contrast to that observed in adipose tissue (Fig. 2I), adiponectin and GLUT4 mRNA did not change significantly in muscle (I). ^cP < 0.05 compared with month 3 (24°C); ^dP < 0.05 compared with month 4 (27°C).