Effects of 24-week pioglitazone versus metformin on activin A levels in type 2 diabetic men. (A) Plasma activin A levels at baseline (BL, light grey) and at 24-weeks follow-up (FU, dark grey) after intervention with pioglitazone (dots) versus metformin (squares) in men with uncomplicated type 2 diabetes (T2D). Differences in plasma activin A levels at BL and FU in each intervention group were analyzed using Wilcoxon matched-pair signed-rank test, between-group differences were performed using linear regression analysis with adjustments for intervention group and baseline values. Pearson correlation analysis showed that changes in activin A levels were not related to changes in MMRglu after either pioglitazone (black dots, black regression line) or metformin (white squares, dashed regression line; B). A marginally significant positive correlation was seen between changes in activin A levels and changes in left ventricular mass/volume ratio (LVMV-ratio) after pioglitazone, not after metformin (C). Changes in activin A levels were not correlated with changes in pulse wave velocity after either pioglitazone (black dots, black regression line) or metformin (white squares, dashed regression line; D).