Plasma follistatin is elevated in patients with type 2 diabetes: relationship to hyperglycemia, hyperinsulinemia, and systemic low-grade inflammation

Background Plasma follistatin is elevated in patients with low-grade inflammation and insulin resistance as observed with polycystic ovary syndrome. In the present study, we evaluated plasma follistatin in patients with type 2 diabetes characterised by low-grade inflammation and assessed the acute effects of hyperglycemia, hyperinsulinemia and LPS on plasma follistatin. Methods Baseline plasma follistatin and inflammatory biomarkers were measured in a cross-sectional study that involved 95 patients with type 2 diabetes and 103 matched controls. To determine the acute effect of hyperglycemia and hyperinsulinemia on follistatin, hyperglycemic and hyperinsulinemic-euglycemic clamps were performed in five healthy males. Furthermore, 15 patients with type 2 diabetes and 22 healthy controls were challenged with low-dose LPS to determine the effect on follistatin. Results Patients with type 2 diabetes have higher HOMA2-IR values mean [95% CI] 1.64 [1.40-1.93] versus mean 0.86 [0.75-0.99], p<0.001 and inflammatory markers compared with controls. Baseline plasma follistatin is elevated in patients with type 2 diabetes compared with controls mean 1564 [1456-1680] versus mean 1328 [1225-1440]ng/L, p=0.003 and correlates with fasting glucose levels (r=0.44, p<0.0001), 2h glucose (r=0.48, p<0.0001), HbA(1c) (r=0.41, p<0.0001), triacylglycerol (r=0.28, p=0.008) and total cholesterol (r=0.33, p=0.004) in patients but not in controls. No correlation exists between plasma follistatin and inflammatory biomarkers in either of the groups. Neither hyperglycemia, hyperinsulinemia nor LPS increase plasma follistatin. Conclusions Plasma follistatin is moderately elevated in patients with type 2 diabetes. Our findings suggest that this is not likely caused by hyperglycemia, hyperinsulinemia or systemic low-grade inflammation. Copyright (c) 2013 John Wiley & Sons, Ltd.