To evaluate the value of the observed dependence of serum GPLD1 amount, activity, and interaction with GPI-APs on the blood glucose and plasma insulin levels for the prediction and diagnosis of metabolic diseases, correlation analyses with determination of putatively positive correlation coefficients will be performed for larger numbers of prediabetic, diabetic, overweight, and obese rats, as well as humans, in the future. Here, GPLD1 is linked to metabolic disease.