What are the normal values for pancreatic islet function?

May 11, 2022 Source: Cainiu Health

Dr. Pan Yongyuan

Introduction

Currently, in clinical practice, pancreatic beta-cell function is primarily assessed using insulin release tests and C-peptide release tests. In healthy individuals, fasting plasma insulin levels are approximately 5–20 mU/L. After oral administration of 75 g anhydrous glucose, plasma insulin peaks within 30–60 minutes, reaching 5–10 times the fasting baseline level, and returns to normal within 3–4 hours.

In daily life, sometimes when we visit a hospital for routine examinations, we may discover that our pancreatic islet function values fall outside the normal range—prompting concern about whether we might have developed a medical condition. So, what are the normal reference values for islet function?

What Are the Normal Reference Values for Islet Function?

Clinically, beta-cell function of the pancreatic islets is primarily assessed using insulin release tests and C-peptide release tests. In healthy individuals, fasting plasma insulin levels typically range from 5–20 mU/L. After oral administration of 75 g anhydrous glucose, plasma insulin peaks within 30–60 minutes, reaching 5–10 times the fasting baseline level; insulin levels then gradually return to baseline within 3–4 hours.

Fasting C-peptide levels are normally above 400 pmol/L. Following oral glucose ingestion, C-peptide also peaks within 30–60 minutes, reaching 5–6 times the fasting baseline. In patients with diabetes, both fasting and peak insulin and C-peptide levels are reduced, and the time to peak is delayed. Additionally, insulin secretion reaches its highest level approximately one hour after a meal. To achieve 5–10-fold (or even 8–10-fold) increases over fasting levels, insulin concentrations decline markedly by two hours postprandially and typically return to near-fasting levels by three hours after eating. Thus, insulin secretion follows a characteristic peak-shaped curve. Since postprandial insulin secretion is commonly assessed in clinical practice, remembering the fasting insulin level allows clinicians to estimate expected postprandial insulin levels.

If you experience any physical discomfort or symptoms, it is advisable to seek timely medical evaluation at a hospital to identify the underlying cause and receive appropriate management. We hope this information proves helpful to you!

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Can insulinoma be cured simply by undergoing surgery?

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