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

## TL;DR

This study found that apelin levels are lower in adolescents with long-term type 1 diabetes compared to recent-onset patients and healthy controls, and apelin correlates with beta-cell function.

## Contribution

The study is the first to show reduced apelin levels in prolonged type 1 diabetes and its association with C-peptide and blood pressure.

## Key findings

- Apelin levels were significantly lower in adolescents with prolonged T1D compared to recent-onset T1D and healthy controls.
- Apelin levels correlated with fasting C-peptide levels, suggesting a link to beta-cell function.
- Myostatin levels in prolonged T1D correlated with higher insulin doses and lower diastolic blood pressure.

## Abstract

Background: 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).

Aim: To assess the levels and clinical correlates of a panel of five
myokines, comparing adolescents with recent‐onset T1D, prolonged disease, and healthy
controls.

Methods: 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.

Results: 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)
p = 0.029). Other myokines did not differ significantly between
groups. Apelin levels correlated with fasting C‐peptide levels
(r = 0.337, p = 0.010). In patients with prolonged
T1D, myostatin positively correlated with insulin doses (total daily dose
r = 0.590, p = 0.006 and basal daily dose
r = 0.645, p = 0.002). Both apelin and myostatin
levels negatively correlated with the diastolic blood pressure (BP) percentile
(r = − 0.324, p = 0.013; r = −
0.302, p = 0.024, respectively).

Conclusions: 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.