Nüchtern - C - Peptid und daraus abgeleitete Parameter zur Charakterisierung der Insulin - Kapazität zwecks korrekter Klassifizierung von Patienten mit Typ 1 - und Typ 2 - Diabetes und zur Vorhersagekraft einer Insulinpflichtigkeit bei Patienten mit Typ 2 - Diabetes
Fasting C-peptide and related parameters characterizing insulin secretory capacity for correctly classifying diabetes type and for predicting insulin requirement in patients with type 2 diabetes
by Florian Sebastian Becht
Date of Examination:2016-12-06
Date of issue:2016-11-11
Advisor:Prof. Dr. Michael Nauck
Referee:Prof. Dr. Dirk Raddatz
Referee:Prof. Dr. Martin Oppermann
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Name:Dissertation F.S.Becht 2016.pdf
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Abstract
English
BACKGROUND/AIMS: C-peptide allows estimation of insulin secretion even in the presence of insulin treatment. C-peptide may be suitable for the differential diagnosis of type 1 and type 2 diabetes, and, within type 2 diabetes, of insulin-requiring vs. non-insulin-requiring patients. Relating C-peptide concentrations to ambient glucose levels might improve its diagnostic potential. PATIENTS/METHODS: The diagnostic value (a) fasting C-peptide, (b) C-peptide/glucose ratios, and (c) the HOMA-ßC-peptide-index for predicting a diagnosis of type 1 (vs. type 2) diabetes were assessed. SETTING: Specialised hospital for the care of diabetic patients (inpatient treatment). 303 patients with type 1 diabetes and 841 patients with type 2 diabetes. MAIN OUTCOME MEASURE: Odds ratios and 95% confidence intervals for a clinical diagnosis of type 1 diabetes or for insulin treatment by deciles of (a) fasting C-peptide, (b) C-peptide/glucose ratios, and (c) HOMA-ßC-peptide-index. RESULTS: Low C-peptide concentrations were associated with a high odds ratio for type 1 diabetes and vice versa (p<0.0001). Concentrations of 0.13-0.36 nmol/l did not discriminate. C-peptide/glucose ratios or HOMA-ßC-Peptide did not perform better. The ability of all 3 parameters to predict the necessity for insulin treatment within the population of type 2-diabetic patients was low. CONCLUSIONS: Fasting C-peptide and derived parameters help to differentiate type 1 from type 2 diabetes, but there is a range of C-peptide concentrations that does not help discriminate. Relating C-peptide to glucose did not improve diagnostic accuracy. C-peptide does not help predicting a need for insulin treatment in patients with type 2 diabetes.
Keywords: C-peptide; fasting C-peptide; C-peptide/glucose ratio; HOMA-ßC-peptide-index; type 1 diabetes; type 2 diabetes; predicting insulin treatment
Schlagwörter: C-Peptid; nüchtern-C-Peptid; C-Peptid/Glukose-Verhältnis; Homa-ßC-Peptid-Index; Typ 1 Diabetes; Typ 2 Diabetes; Insulinpflicht