FSTL3 and diabetes mellitus: Additionally, serum FSTL3 levels were positively correlated with BMI, waist circumference, fat mass, and body fat percentage.[45] Perakakis et al discovered that FST levels in morbidly obese patients, both with and without T2DM, significantly decreased following weight loss surgery.[41] Similarly, Wiewiora et al also confirmed that in morbidly obese individuals without diabetes, there was a drop in circulating FST concentrations 1 year after undergoing weight loss surgery.[46]