Apelin and Myostatin Levels in Adolescents With Type‐1‐Diabetes

<b>Background:</b> Myokines are secreted by skeletal muscle and play a role in their metabolic function and crosstalk with various tissues. Myokines appear to be involved in the pathogenesis of obesity and type 2 diabetes (T2D), yet little is known regarding their function in type 1 diabetes (T1D). <b>Aim:</b> To assess the levels and clinical correlates of a panel of five myokines, comparing adolescents with recent-onset T1D, prolonged disease, and healthy controls. <b>Methods:</b> Fifty-eight adolescents participated; 20 with recent-onset T1D, 20 with over 7 years of T1D, and 18 healthy controls were included. Clinical and laboratory data were collected, including levels of Apelin, Irisin, Interleukin-6 (IL-6), Fibroblast growth factor 21 (FGF21), and Myostatin. <b>Results:</b> Apelin levels were lower in patients with prolonged T1D compared with patients with recent-onset T1D and controls, (117.9 ± 94.3, 228.3 ± 181.6, and 224.4 ± 138.4 pg/ml, respectively; analysis of variance (ANOVA) <i>p</i> = 0.029). Other myokines did not differ significantly between groups. Apelin levels correlated with fasting C-peptide levels (<i>r =</i> 0.337, <i>p</i> = 0.010). In patients with prolonged T1D, myostatin positively correlated with insulin doses (total daily dose <i>r =</i> 0.590, <i>p</i> = 0.006 and basal daily dose <i>r =</i> 0.645, <i>p</i> = 0.002). Both apelin and myostatin levels negatively correlated with the diastolic blood pressure (BP) percentile (<i>r =</i> - 0.324, <i>p</i> = 0.013; <i>r</i> = - 0.302, <i>p</i> = 0.024, respectively). <b>Conclusions:</b> Our results demonstrate lower levels of apelin, a myokine related to the beneficial metabolic effects of skeletal muscle, in prolonged T1D. The correlations of apelin with C-peptide and myostatin with insulin doses may reflect a relationship with beta-cell function and insulin sensitivity.