C-peptide is a byproduct produced along with insulin in the pancreas. C-peptide by itself does not have a physiological effect. Insulin on the other hand, has the vital role in taking up glucose from the bloodstream to provide the body with energy.
Normal levels of C-peptide indicate that your pancreas is producing adequate amounts of insulin to help regulate blood sugar levels.
Being an indicator of insulin production and secretion in the body, C-peptide is used as a biomarker for diagnosing diabetes, differentiating between type 1 and type 2 diabetes, monitoring diabetes and assessing effectiveness of insulin therapy in patients with diabetes.
Apart from this, C-peptide is relevant when evaluating and monitoring pancreas function, which may be affected in conditions such as pancreatitis and pancreatic cancer.
High C-peptide levels indicate that the body either produces too much insulin, or that the body cannot effectively use the insulin being produced. A high C-peptide level can indicate insulin resistance, and if the glucose level is simultaneously also elevated, it may indicate pre-diabetes. If an elevated value is received, a new blood test needs to be taken before any conclusions can be made.
Low C-peptide levels indicate that the body either produces insufficient amounts of insulin or that there is a lower than normal need for insulin production in the body. Lower than normal needs include prolonged fasting and very low carbohydrate diets.
Insufficient production and secretion however, are most often a result of type 1 diabetes or advanced type 2 diabetes. Certain medications may also result in low C-peptide levels, such as sulfonylureas or meglitinides.
Important note: Low C-peptide levels together with elevated glucose levels should be evaluated and further investigated by your healthcare provider.