Reassessing diabetes type with C peptide and feasibility of transitioning therapy from insulin to non-insulin therapy

Abstract Background and aim Measurement of islet cell antibodies could be helpful in determining the etiology of diabetes but may not be detected at diagnosis in individuals with type 1 diabetes. Additionally, “false positive” antibody test results may arise, particularly if only one antibody is detectable at low titer. C-peptide measures endogenous insulin synthesis. Our study aimed to assess the role of C-peptide in reclassifying type of diabetes and remapping therapy plan. Patients and methods Our study is a cross sectional with a small uncontrolled pilot intervention, enrolling 56 diabetic patients classified ≥ 3 years, type (1), based on age, phenotypical criteria “absence of insulin resistance signs”. They were all on basal bolus insulin therapy and attending Students Hospital Outpatients Clinic, Mansoura University for their regular follow up. Diabetes control and β cell reserve were checked at time of survey by estimation of HbA1c, C peptide assessment 120 min postprandial while blood glucose is between 80 and 180 mg/dl. For those reclassified as type “2”, based on C-peptide, received oral therapy and HbA1c was checked after 3 months. Results The study enrolled 56 patients, with a median of age 20 (19-21.75) years. 11 (19.64%) patients had history of diabetic ketoacidosis (DKA). At time of survey, C-peptide was low < 0.6 ng/mL in 87.5% of the recruited patients, while 12.5% showed C-peptide level more than 0.6ng/mL. 5(8.9%) patients had C peptide > 1.8 ng/mL, they were tested negative for anti-GAD65 and reclassified as type (2) diabetes. Patients who shifted to oral therapy experienced improved HbA1c after 3 months. Conclusion Measuring C-peptide in clinical practice can be a cost-effective method for classifying diabetes types and selecting appropriate care plans.