Observational Study of C-peptide Levels in Youth With Longstanding Type 1 Diabetes Mellitus as Detected by an Ultrasensitive Assay

Background Type 1 diabetes is characterized by pancreatic beta-cell destruction and an inability to synthesize insulin. Connecting peptide (C-peptide) is formed from the same precursor as insulin and is produced in equimolar amounts as insulin. There are several clinical trials currently being performed to explore the possibility of beta-cell preservation or regeneration. Most children are not eligible for these trials because it is often presumed that C-peptide levels will decrease and become undetectable after years of having type 1 diabetes. Several studies in the adult population have demonstrated that C-peptide may remain measureable in patients who have had diabetes for up to 50 years after diagnosis. Recently, it was demonstrated that 10% of adult patients who have had type 1 diabetes for 31-40 years have measureable levels of serum C-peptide if measured with an ultrasensitive assay. The levels were lower in patients who had diabetes for a longer time. This pattern was also demonstrated in the Diabetes Control and Complications Trial (DCCT) and NHANES trial. No studies have been performed exclusively in pediatric patients Hypothesis The investigators hypothesize that C-peptide should be detectable in the sera of pediatric patients who have had type 1 diabetes for greater than 1 year and as far out as > 20 years after diagnosis. The investigators also hypothesize that since their patient population has had diabetes for less time as compared to adults, the levels of C-peptide should be higher than reported for adults and that a greater proportion of patients in the pediatric population will have detectable C-peptide levels as compared to adults.