Clinical Utility of Serial Monitoring of C-Peptide in Diagnostic Dilemmas of Young-Onset Diabetes: A Case-Based Discussion

Abstract Diabetes in the young has been traditionally defined as onset of diabetes below 35 years of age. In this age bracket, a variety of distinct types of diabetes might occur which poses a unique challenge in the diagnosis and management. Phenotypic features such as age of onset, presence of obesity and family history have traditionally been used in differentiating the various types of diabetes. With the increasing prevalence of obesity and T2DM in youth, these features have become less reliable in classifying diabetes in this age group. Along with detailed patient history and physical examination, biochemical parameters such as C-peptide and presence or absence of pancreatic autoantibodies (along with imaging studies for pancreatic pathology and genetic testing for monogenic forms of diabetes) are assuming greater importance in appropriate diagnosis and understanding the types of diabetes. C-peptide test which is a proxy for pancreatic beta cell function plays an important role in classifying type / subtypes of diabetes. When used appropriately it also helps in personalized approach to treatment and practice of Precision Diabetes.