ECE2017 Guided Posters Diabetes therapy & complications 2 (10 abstracts)
1Gartnavel General Hospital, Glasgow, UK; 2Glasgow Royal Infirmary, Glasgow, UK.
Introduction: C-peptide is frequently used in clinical practice to estimate insulin secretion, and guide need for future insulin treatment. Present practice is based on studies with small patient numbers.
Aim: To explore the association between non-stimulated c-peptide and progression to insulin therapy in patients with diabetes.
Patients and Methods: 1971 patients with c-peptide measurements were identified (February 2007December 2016) within a single health board. 940 individuals also appeared on national diabetes database. 872 individuals within this dataset have a defined diabetes diagnosis and were analysed. The date of first encashed insulin prescription for each individual was extracted from the national diabetes dataset. Insulin-free survival (time to first insulin prescription or end of follow-up) in individuals who were insulin-naive at the time of c-peptide measurement was investigated using survival analysis. Individuals with c-peptide values below median were compared with those above median value. Time to insulin prescription was analysed using cox proportional hazard model with age and BMI as covariables. The positive predictive value (PPV) of c-peptide for predicting insulin use at 1 year was calculated in 0.2 nmol/l increments.
Results: 458 individuals had BMI data available, and were insulin-naive at the time of c-peptide measurement. In this cohort a c-peptide in the lower half of the range of observed values (<0.76 nmol/l) is associated with a significantly decreased insulin-free survival time (P<0.001, HR 3.0). PPV for initial c-peptide(nmol/l) increments were: c-peptide 0.01-0.2 PPV=0.95, 0.20.4 PPV=0.67, 0.40.6 PPV=0.6, 0.60.8 PPV=0.43, 0.81.0 PPV=0.3.
Conclusion: Unstimulated c-peptide is independently associated with increased probability of requiring insulin at 1 year. This is a simple test which offers potentially useful information allowing patients to plan for future treatment.