Fasting plasma C-peptide, glucagon stimulated plasma C-peptide, and urinary C-peptide in relation to clinical type of diabetes

Diabetologia. 1989 May;32(5):305-11. doi: 10.1007/BF00265547.


Many patients with Type 2 (non-insulin-dependent) diabetes mellitus are treated with insulin in order to control hyperglycaemia. We studied fasting plasma C-peptide, glucagon stimulated plasma C-peptide, and 24 h urinary C-peptide in relation to clinical type of diabetes in 132 insulin treated diabetic subjects. Patients were classified clinically as Type 1 (insulin-dependent) diabetic subjects in the presence of at least two of the following criteria: 1) significant ketonuria, 2) insulin treatment started within one year after diagnosis, 3) age of diagnosis less than or equal to 40 years, and 4) weight below 110% of ideal weight of the same age and sex. Eighty patients were classified as Type 1 and 52 as Type 2 diabetic subjects. A second classification of patients into 6 C-peptide classes was then performed. Class I consisted of patients without islet B-cell function. Class II-VI had preserved islet B-cell function and were separated according to the 20%, 40%, 60% and 80% C-peptide percentiles. The two classifications of patients were compared by calculating the prevalence of clinical Type 1 and Type 2 diabetes in each of the C-peptide classes. This analysis showed that patients with a fasting plasma C-peptide value less than 0.20 nmol/l, a glucagon stimulated plasma C-peptide value less than 0.32 nmol/l, and a urinary C-peptide value less than 3.1 nmol/l, or less than 0.54 nmol/mmol creatinine/24 h, or less than 5.4 nmol/24 h mainly were Type 1 diabetic patients; while patients with C-peptide levels above these values mainly were Type 2.(ABSTRACT TRUNCATED AT 250 WORDS)

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • C-Peptide / blood*
  • C-Peptide / urine
  • Diabetes Mellitus, Type 1 / blood*
  • Diabetes Mellitus, Type 1 / urine
  • Diabetes Mellitus, Type 2 / blood*
  • Diabetes Mellitus, Type 2 / urine
  • Fasting
  • Female
  • Glucagon*
  • Humans
  • Insulin / blood
  • Insulin / metabolism
  • Insulin Secretion
  • Male


  • C-Peptide
  • Insulin
  • Glucagon