Table 2

Fasting and stimulated C-peptide and proinsulin values

VariableC-peptide <0.017 nmol/L (n = 99)C-peptide 0.017–0.2 nmol/L (n = 117)C-peptide ≥0.2 nmol/L (n = 103)Control subjects (n = 12)
Fasting C-peptide (nmol/L)n/a0.023 (<0.017, 0.036)***#0.156 (0.095, 0.30)*0.601 (0.525, 0.800)
Stimulated (90 min) C-peptide (nmol/L)n/a0.079 (0.040, 0.111)***#0.513 (0.344, 0.847)*1.84 (1.08, 2.47)
Fasting proinsulin (pmol/L)13.5 (6.2, 23.8)10.9 (7.3, 21.5)15.2 (9.8, 23.8)15.19 (11.8, 17.4)
Stimulated (90 min) proinsulin (pmol/L)11.2 (4.6, 19.7)***#11.3 (7.3, 34.8)***#22.5 (17.1, 34.8)46.7 (34.3, 74.2)
Fasting PI:C ration/a37.7 (22.0, 58.5)***#9.6 (5.9, 18.1)**2.3 (2.0, 3.1)
Stimulated PI:C ration/a15.4 (8.4, 27.9)***#4.9 (2.4, 6.9)2.6 (2.4, 3.2)
  • Data represent values obtained at initial visit and are expressed as median (interquartile range). n/a, not applicable.

  • *P < 0.05;

  • **P < 0.01;

  • ***P < 0.001 compared with control subjects and

  • #P < 0.001 compared with C-peptide ≥0.2 nmol/L group using Kruskal-Wallis test with Dunn multiple comparisons test.