No Correlation between Serum Progranulin Levels and Severity of Diabetic Retinopathy in Chinese People with Type 2 Diabetes and Normal or Mildly Impaired Renal Function

Abstract Background: Progranulin (PGRN), a novel pro-inflammatory adipokine, was reported to be related to the development and progression of diabetic retinopathy(DR). However, recently PGRN was established as a renal function-dependent protein, but no data regarding PGRN and DR excluded the influence of decreased renal elimination. This study aimed to investigate the correlation between serum PGRN and DR excluding the effect of deteriorating renal function. Methods: 338 subjects with estimated glomerular filtration rate (eGFR) ≥ 60 ml/min/1.73m2 were divided into four groups of normal controls (NC)(n=76), simple diabetes mellitus (SDM)(n=195) , nonproliferative diabetic retinopathy (NPDR)(n=41), and proliferative diabetic retinopathy (PDR)(n=26). Serum PGRN was quantified by enzyme-linked immunosorbent assay, and further analyses of serum PGRN in different groups were conducted. Results: There was no significant difference of serum PGRN between NC, SDM, NPDR, and PDR groups (P>0.05). Serum PGRN in all subjects negatively and significantly correlated with eGFR (r=-0.144, P<0.05), triglycerides and glucose (TyG) index (r=-0.127, P<0.05), and triglyceride (TG) (r=-0.132, P<0.05), while positively and significantly correlated with low-density lipoprotein cholesterol (LDL-C) (r=0.140, P<0.05). Multivariate stepwise regression analysis indicated only LDL-C (β=1.030, P<0.05) was independently associated with serum PGRN. Conclusions: We demonstrated that serum PGRN levels did not correlate with severity of DR in Chinese patients with type 2 diabetes and eGFR ≥ 60ml/min/1.73m2, but positively and independently correlated with LDL-C.