Hello Doctor,

Administration of exogenous insulin suppresses pancreas function of producing endogenous insulin in the case of type 2 Diabetes Mellitus.

It doesn’t get mix with the c peptide directly, but it does affect endogenous insulin and c peptide synthesis.

So it is recommended to stop Insulin before undergoing C Peptide test.

With hold insulin as per its type,

Hold Short Acting insulin for minimum 8hrs
Hold Intermediate acting insulin for minimum 12 hrs
Hold Long acting insulin for minimum 24hrs

Also, C Peptide test alone is not completely reliable for diagnosing Hypoinsulinemia or Type 1 Diabetes.

Along with C peptide, look for the below conditions to arrive at the diagnosis of type 1 diabetes.

1. Onset of DM less than 30yrs of age

2. Patient BMI less than 21

3. If the patient has suffered from Diabetes ketoacidosis anytime in his life

4. HBA1C is recorded high above 16 anytime in his life.

5. Onset of DM after suffering from any critical illness like acute pancreatitis, covid etc ,Chemotherapy or Surgery.

6. Patient BSL not responding to more than 3 OHA and having hba1c more than 14.

These above conditions along with low C Peptide levels helps us to diagnose  Type 1 DM, Hypoinsulinemia condition.,

Lifestyle modification, Low Carb Diet, Exercise, Yogasana,  Stress management , Panchkarma and Ayurvedic medicines helps in managing BSL in both the cases.