Categorical analysis of C peptide and insulin with severity of diabetic retinopathy and corresponding renal functions
| No DR | Mild NPDR | Moderate NPDR | Severe NPDR | PDR | p Value of different models | ||||
|---|---|---|---|---|---|---|---|---|---|
| (n=256) | (n=97) | (n=132) | (n=25) | (n=75) | 1 | 2 | 3 | 4 | |
| Biomarker | |||||||||
| C peptide (nmol/L) | 1.23±0.04 | 1.06±0.07 | 0.82±0.06 | 0.87±0.14 | 1.14±0.08 | 4.7×10−7 | 0.001 | 0.002 | 0.002 |
| Insulin (μU/mL)* | 13.69±0.60 | 12.20±1.01 | 9.08±0.99 | 9.36±2.28 | 8.47±1.47 | 8.6×10−9 | 0.0008 | 0.001 | 0.01 |
| Renal functions | |||||||||
| Serum creatinine (mg/dL) | 0.76±0.06 | 0.76±0.10 | 0.99±0.09 | 0.90±0.20 | 1.84±0.11 | ||||
| Urinary albumin-to-creatinine ratio | 33.5±74 | 41.0±120 | 431.8±102 | 404.0±235 | 1420.3±144 | ||||
| CKD-EPI eGFR (mL/min/1.73 m2) | 98.5±1.5 | 100.5±2.5 | 94.1±2.1 | 93.9±4.9 | 68.2±2.8 | ||||
Mean values and significance of biomarkers by severity of diabetic retinopathy adjusted for different covariates in different models. Value depicted as mean±SE of the mean.
*Analysis for insulin was conducted in participants without exogenous insulin injection (n=406). Models: 1=adjusted for family structure; 2=adjusted for family structure, age, gender, HbA1c, diabetes duration, systolic blood pressure and serum creatinine; 3=adjusted for family structure, age, gender, HbA1c, diabetes duration, systolic blood pressure, and urinary albumin-to-creatinine ratio; 4=adjusted for family structure, HbA1c, diabetes duration, systolic blood pressure, and CKD-EPI eGFR.
CKD-EPI, Chronic Kidney Disease Epidemiology Collaboration equation; DR, diabetic retinopathy; eGFR, estimated glomerular filtration rate; HbA1c, glycosylated hemoglobin; NPDR, non-proliferative diabetic retinopathy; PDR, proliferative diabetic retinopathy.