INS and Insulin resistance: Insulin resistance was associated with decreased brain glucose metabolism during fasting [−0.47 SD, 95% confidence interval (CI): −0.73 to −0.22, P < .001, I2 = 71%] and increased metabolism during insulin stimulation (1.44 SD, 95% CI 0.79 to 2.09, P = .002, I2 = 43%).