FNDC5 and myotonic dystrophy type 1: The analysis of the correlations between plasma irisin levels and anthropometric and metabolic parameters showed a distinct pattern in DM1 and DM2 patients, respectively, in DM1 patients, plasma irisin levels correlated negatively with oxygen consumption and positively with insulin resistance, while in DM2 patients plasma irisin levels positively correlated with fat mass at arms and legs levels.