Table 5. Comparisons between patients in different level of postprandial C-peptide.
| Lowest quartile | Second quartile | Third quartile | Highest quartile# | |
| age (years) | 57.6±14.6 | 57.3±13.3 | 57.1±13.0 | 58.0±12.4 |
| Age at diagnosis of diabetes (years)* | 46.5±13.1 | 47.4±11.7 | 48.6±11.6 | 50.5±11.6 |
| Duration of diabetes (years)* | 11.0±8.9 | 9.9±7.6 | 8.5±7.4 | 7.6±6.1 |
| BMI (kg/m2)* | 23.4±3.1 | 25.1±3.1 | 26.0±3.4 | 26.3±3.8 |
| HbA1c (%)* | 10.3±2.4 | 9.5±2.0 | 9.1±2.0 | 8.2±1.8 |
| Fasting C-peptide (ng/dl)* | 0.97±0.42 | 1.52±0.55 | 1.91±0.69 | 2.78±1.18 |
| Postprandial C-peptide (ng/dl)* | 1.40±0.45 | 2.71±0.38 | 4.23±0.55 | 7.75±2.14 |
| prevalence of primary hypertention (%)* | 45 | 50 | 54 | 63 |
| prevalence of DR (%)* | 34 | 26 | 21 | 15 |
| prevalence of PDR (%) | 23 | 29 | 19 | 23 |
| prevalence of peripheral vascular sclerosis (%) | 80 | 82 | 81 | 80 |
| patients with insulin treatment (%)* | 55 | 54 | 41 | 29 |
*comparison among groups showed significant difference.
#lowest quartile: postprandial C-peptide≤2.1 ng/dl; second quartile: 2.1 ng/dl < postprandial C-peptide≤3.41 ng/dl; third quartile: 3.41 ng/dl < postprandial C-peptide≤5.33 ng/dl; highest quartile: 5.33 ng/dl < postprandial C-peptide.
Abbreviations in the tables: DR: diabetic retinopathy; PDR: proliferative diabetic retinopathy; BMI: body mass index; HbA1c: hemoglobin A1c.