💡 What You Need to Know Right Away
A C-Peptide test is a blood test that measures how much insulin your pancreas produces naturally, helping doctors classify diabetes type (Type 1 vs Type 2), detect pancreatic tumors, and guide treatment decisions. Unlike regular insulin tests, this test measures only your body's own insulin production, making it accurate even if you take insulin injections.
Also known as: C-peptide, Connecting Peptide Test, Insulin C-Peptide Test, C-Peptide Serum
- Research shows results at or below 0.20 nmol/L indicate Type 1 diabetes, while results at or above 0.30 nmol/L indicate Type 2 diabetes[Evidence: A][1]
- This test correctly identifies Type 1 diabetes in about 93 out of 100 cases when using optimal cutoff values[Evidence: C][2]
- Clinical guidelines recommend results at or above 600 pmol/L (≥1.8 ng/mL) are conclusive for Type 1 diabetes[Evidence: D][15]
- The urine version of this test offers a non-invasive alternative that works well for most people[Evidence: D][19]
If your doctor has ordered a C-Peptide test, you may be wondering what it measures and what your results will mean. It's common to feel uncertain when facing a new medical test, especially one related to diabetes diagnosis or management.
This test provides valuable information that other diabetes tests cannot offer. While blood glucose tests tell you how much sugar is in your blood right now, and HbA1c shows your average blood sugar over months, the C-Peptide test reveals something different. It measures how well your pancreas is producing insulin. This matters because understanding your insulin production helps doctors determine the best treatment approach for your specific situation.
In this guide, you'll learn what the test measures, how to prepare, what your results mean, and when this test is most useful. Whether you're newly diagnosed with diabetes or monitoring an existing condition, understanding your C-Peptide results puts you in a better position to work with your healthcare team.
❓ Quick Answers
What is a C-Peptide test?
A C-Peptide test is a blood test that measures how much insulin your pancreas produces naturally. Your body makes equal amounts of C-peptide and insulin, but C-peptide stays in your blood longer, making it easier to measure accurately. This test helps doctors classify diabetes type and guide treatment decisions[Evidence: D][19].
What is a C-Peptide test used for?
Doctors order this test to distinguish Type 1 from Type 2 diabetes, detect insulin-producing pancreatic tumors (insulinoma), investigate unexplained low blood sugar, and monitor how well diabetes treatments are working. Research shows using all three measurements together—glucose, insulin, and C-peptide—correctly identifies insulinoma in 100 out of 100 cases[Evidence: D][16].
What are normal C-Peptide levels?
Research shows results at or below 0.20 nmol/L indicate Type 1 diabetes, while results at or above 0.30 nmol/L indicate Type 2 diabetes[Evidence: A][1]. Clinical guidelines recommend results at or above 600 pmol/L (≥1.8 ng/mL) are conclusive for Type 1 diabetes, while results between 200-600 pmol/L usually indicate Type 1 diabetes or MODY[Evidence: D][15].
Do I need to fast for a C-Peptide test?
Fasting requirements depend on the test type your doctor orders. A fasting test requires 8-12 hours without food. Clinical guidelines note that random nonfasting C-peptide is convenient and performs well for many situations[Evidence: D][19]. Ask your healthcare provider which version they're ordering.
Is a C-Peptide test safe?
The standard blood draw version is very safe with minimal risks. You may experience brief discomfort, minor bruising, or lightheadedness. The stimulated version using glucagon injection has more side effects. Adverse effects occurred in about 43 out of 100 people during the glucagon version, including nausea in about 30 out of 100 cases[Evidence: D][11].
How accurate is a C-Peptide test?
This test demonstrates excellent accuracy for classifying diabetes. In people being tested for Type 1 diabetes, the test correctly identified the condition in about 93 out of 100 cases[Evidence: C][2]. For insulinoma detection, research shows accuracy of about 87 out of 100 cases using an oral glucose test approach[Evidence: A][10].
What does low C-Peptide mean?
Low C-Peptide results (below 0.2 nmol/L) indicate your pancreas is producing little insulin, which is associated with Type 1 diabetes diagnosis[Evidence: D][19]. Very low results below 80 pmol/L (<0.24 ng/mL) typically do not require repeat testing[Evidence: D][15]. Your doctor will interpret your specific results in context.
C-Peptide Blood Test
A window into your body's insulin production. Understand how your pancreas functions and what your levels reveal about your health.
🔬 How Does the C-Peptide Test Work?
To understand this test, think of your pancreas as a factory that produces insulin. When your pancreas makes insulin, it actually creates a larger molecule called proinsulin first. This proinsulin molecule then splits into two parts: the active insulin that controls your blood sugar, and a byproduct called C-peptide (the "C" stands for "connecting" because it connects the two parts of proinsulin).
Think of C-peptide as a receipt from your pancreas. Every time your pancreas produces one molecule of insulin, it also produces exactly one molecule of C-peptide. By counting these "receipts," doctors can determine how much insulin your body is making on its own.
This matters because C-peptide has a longer "shelf life" in your blood. Insulin breaks down within 3-5 minutes, but C-peptide stays around for 30-35 minutes. This longer presence makes C-peptide easier to measure accurately. Studies show correlations of r=0.74-0.9 between different test methods, confirming this approach reliably captures your pancreas function[Evidence: B][7].
The test is especially valuable because it measures only your body's own insulin production. If you take insulin injections, injected insulin does not produce C-peptide. This means doctors can accurately assess your pancreas function regardless of insulin therapy. Research validates C-peptide as a reliable marker. When treatments preserve about 25% more C-peptide, patients have about 0.5% lower hemoglobin A1c levels[Evidence: A][18].
What the Test Reveals About Diabetes Type
In Type 1 diabetes, the immune system destroys the insulin-producing beta cells in the pancreas. With fewer beta cells, C-peptide production drops significantly. Research shows cutoff values at or below 0.20 nmol/L indicate Type 1 diabetes[Evidence: A][1].
In Type 2 diabetes, the pancreas still produces insulin, but the body doesn't use it effectively (insulin resistance). C-peptide levels are typically normal or even elevated. Research shows cutoff values at or above 0.30 nmol/L indicate Type 2 diabetes[Evidence: A][1].
The test also helps identify insulinoma, a rare pancreatic tumor that produces excess insulin. In this condition, C-peptide levels are high even when blood sugar is dangerously low. Research shows using all three measurements—glucose, insulin, and C-peptide together—correctly identifies insulinoma with 100% sensitivity and 89% specificity[Evidence: D][16].
Studies also suggest people with elevated C-peptide levels in the general population are more than twice as likely to develop Type 2 diabetes over the next 7 years[Evidence: C][20], showing the test may help identify people at higher risk before symptoms appear.
🧪 What to Expect: The Real User Experience
During the Blood Draw
You'll feel tourniquet tightness on your upper arm for 5-10 seconds, similar to a blood pressure cuff squeeze. The phlebotomist applies an elastic band above your elbow to make veins visible. An antiseptic wipe feels cool on your skin for 2-3 seconds before needle insertion. The room temperature is typically 68-72°F and may feel cool in a hospital gown.
The needle prick sensation lasts 3-5 seconds, similar to a bee sting or pinch. Most people describe it as 2-3 out of 10 on a pain scale. A throbbing sensation is possible during blood collection, which takes 1-2 minutes. The actual needle-in-arm time is typically 30-60 seconds. The sensation resolves immediately after needle removal.
What You'll Feel After
Minor bruising at the needle site occurs in about 20-30% of patients and resolves in 3-5 days. Tenderness or soreness may last 1-2 hours, especially if multiple vials were drawn. If you fasted, dizziness or lightheadedness affects 5-10% of patients but resolves after eating. Fainting is rare, occurring in less than 2% of patients, typically in those with needle anxiety.
How to Make It Easier
- For needle anxiety: Look away during insertion. Ask the phlebotomist to warn you before the needle stick. Practice deep breathing: inhale 4 counts, exhale 6 counts.
- For fainting risk: Inform staff if you've fainted before. Request to lie down during the draw instead of sitting. Eat a small snack beforehand if it's a non-fasting test.
- For difficult veins: Stay well-hydrated the day before. Avoid caffeine, which constricts veins. Wear short sleeves or loose clothing.
- For bruising prevention: Apply firm pressure with gauze for 3-5 minutes after needle removal. Avoid heavy lifting with that arm for 2-3 hours. Don't rub the site.
- For children: Use numbing cream (EMLA or LMX) 30-60 minutes before if available. Bring a distraction like a tablet or toy. Ask if a butterfly needle is available.
📊 Preparation and Test Procedure
Your preparation depends on which type of C-Peptide test your doctor orders. There are several variations, each providing different information.
| Test Type | Preparation Required | Duration | Best For |
|---|---|---|---|
| Fasting C-Peptide | Fast 8-12 hours (water OK) | 5-10 minutes | Baseline measurement[Evidence: D][19] |
| Random (Non-fasting) | None | 5-10 minutes | Convenient screening[Evidence: D][19] |
| Mixed Meal Tolerance Test (MMTT) | Fast overnight, then drink standardized shake | 2-3 hours (multiple draws) | Beta cell reserve assessment (R² = 0.96 reproducibility)[Evidence: B][6] |
| Glucagon Stimulation Test (GST) | Fast overnight, receive glucagon injection | 30-60 minutes | Stimulated response (more side effects)[Evidence: B][6] |
| Urine C-Peptide (UCPCR) | Collect urine sample after meal | 5 minutes | Non-invasive alternative[Evidence: A][4] |
Preparation Checklist
- Confirm fasting requirements with your doctor or lab
- If fasting, water is usually allowed
- List all medications you take (some may affect results)
- Wear short sleeves or loose clothing
- Bring a snack to eat after a fasting test
- Arrange transportation if you feel dizzy after fasting
Test Variations Explained
Mixed Meal Tolerance Test (MMTT): Studies suggest this test shows excellent consistency when repeated, with very reliable results (R² = 0.96)[Evidence: B][6]. Patients prefer this version over the glucagon injection version[Evidence: B][6]. You drink a standardized nutritional shake, then have blood drawn at specific intervals to see how your pancreas responds.
Glucagon Stimulation Test: This test uses an injection of glucagon hormone to stimulate insulin release. Studies suggest nausea is common with this version[Evidence: B][6]. Clinical guidelines recommend the glucagon stimulation test provides a balance of sensitivity and practicality[Evidence: D][19].
Urine C-Peptide Creatinine Ratio (UCPCR): This non-invasive option measures C-peptide in urine. Research shows it correctly identifies Type 1 diabetes in about 84 out of 100 cases with results below 0.2 nmol/mmol[Evidence: A][4].
Newer Options: Studies suggest the skin patch version (transdermal sampling) correctly detected C-peptide levels in 100 out of 100 cases when levels were at or above 200 pmol/L[Evidence: C][13]. Most people prefer the skin patch version over traditional blood draw[Evidence: C][13].
⚠️ Risks, Side Effects, and Warnings
The standard blood draw C-Peptide test is very safe with minimal risks—the same as any routine blood test. Most people tolerate the test well. It's normal to feel anxious about medical tests, but this test involves only a simple blood draw.
⚠️ Important Safety Information
- Standard blood draw risks: Brief pain, bruising at puncture site, lightheadedness (especially if fasting), rare infection risk
- Glucagon stimulation test: Adverse effects occurred in about 43 out of 100 people, including nausea (about 30%), vomiting (about 27%), and abdominal cramps (about 19%)[Evidence: D][11]
- Elderly caution (>67 years): Severe low blood pressure occurred in about 10 out of 100 elderly people during glucagon testing. Seizures occurred in about 2 out of 100 cases[Evidence: D][12]
- Age consideration: Side effects from glucagon testing are more common in patients over 50 years[Evidence: D][11]
Factors That May Affect Results
Early research suggests test results can vary significantly depending on which lab equipment is used, with differences up to 37% between some platforms[Evidence: C][5]. Expert consensus notes test results can vary between laboratories, which may affect how results are interpreted[Evidence: D][17]. Early research also suggests some lab platforms show better agreement, with differences of only 2-4% between results[Evidence: C][5].
Because of this variability, always interpret your results using your specific laboratory's reference ranges. If monitoring C-peptide over time, try to use the same laboratory for consistent comparisons.
When to Seek Medical Attention
Contact your healthcare provider if you experience:
- Excessive bleeding or swelling at the puncture site
- Signs of infection (increasing redness, warmth, discharge)
- Prolonged dizziness or fainting that doesn't resolve with rest and food
- Severe nausea or vomiting after a glucagon stimulation test
🥗 What to Do After Getting Your Results
Understanding Your Results in Context
Your C-Peptide result is one piece of a larger puzzle. Your doctor will interpret it alongside your blood glucose levels, HbA1c, symptoms, and medical history. Here's general guidance on what different results may indicate:
| C-Peptide Level | What It May Indicate | Typical Next Steps |
|---|---|---|
| Very low (<0.2 nmol/L or <0.6 ng/mL) | Type 1 diabetes (pancreas producing little insulin)[Evidence: D][19] | Insulin therapy typically required. Discuss management plan with endocrinologist. |
| Low-normal (0.2-0.6 nmol/L) | Possible Type 1 diabetes, LADA, or MODY[Evidence: D][15] | May need additional testing (antibody tests, genetic testing). Discuss with specialist. |
| Normal to high (>0.6 nmol/L or >1.8 ng/mL) | Type 2 diabetes or insulin resistance[Evidence: A][1] | May respond to lifestyle changes or oral medications. Discuss options with doctor. |
| High with low blood sugar | Possible insulinoma or other conditions[Evidence: D][16] | Further testing needed. Referral to endocrinologist likely. |
Questions to Ask Your Doctor
- What does my specific C-Peptide result mean for my diagnosis?
- Do I need any follow-up tests?
- How does this result affect my treatment plan?
- Should I repeat this test in the future? If so, when?
- Should I see an endocrinologist based on these results?
If You Have Diabetes
Studies suggest this test helps identify which patients with Type 2 diabetes need insulin or other medications to help their pancreas[Evidence: C][8]. If your C-Peptide is declining over time, your doctor may recommend adjusting your treatment. Regular monitoring can help optimize your diabetes management.
What to Look for When Choosing a C-Peptide Test Provider
The quality of your test results depends on the lab and healthcare provider. Here's what to consider:
Lab Quality Markers
- CLIA certification: Clinical Laboratory Improvement Amendments (CLIA) accreditation required Why it matters: Federal quality standards ensure accurate results
- CAP accreditation: College of American Pathologists certification (higher standard than CLIA) Why it matters: Rigorous proficiency testing and inspections
- Assay platform consistency: Early research suggests some lab platforms show better agreement (2-4% bias) than others (up to 37% bias)[Evidence: C][5] Why it matters: If monitoring over time, use the same lab for consistent comparisons
- Turnaround time: Ask about expected results timeline (typically 1-3 days for routine testing) Why it matters: Faster results enable quicker treatment decisions
- Insurance acceptance: Verify in-network status before testing Why it matters: Out-of-network labs can cost significantly more
Questions to Ask Your Provider
- Which type of C-Peptide test are you ordering (fasting, random, stimulated)?
- Do I need to fast or prepare in any specific way?
- When will results be available?
- Who will explain my results to me?
- What's the cost if my insurance doesn't cover it?
- Should I use a specific lab for this test?
Red Flags to Avoid
- No CLIA certification: Unlicensed labs lack quality oversight
- Unusually cheap pricing: May indicate unaccredited lab or limited quality controls
- Pressure to add-on tests: Unnecessary tests inflate costs without medical benefit
- No reference ranges provided: Results without context are difficult to interpret
C-Peptide Test vs Insulin Test: What's the Difference?
C-Peptide testing and insulin testing both measure aspects of your body's insulin system, but they serve different purposes and provide complementary information. Here's how they compare:
| Feature | C-Peptide Test | Insulin Test |
|---|---|---|
| What it measures | Endogenous (body's own) insulin production only | Total insulin (both injected and body's own) |
| Half-life in blood | 30-35 minutes (longer, more stable measurement) | 3-5 minutes (shorter, more variable) |
| Accurate with insulin therapy | Yes - unaffected by insulin injections[Evidence: D][19] | No - cannot distinguish injected from endogenous insulin |
| Best clinical use | Classify diabetes type (T1D vs T2D); assess beta cell function[Evidence: A][1] | Assess insulin resistance; calculate HOMA-IR index |
| Insulinoma detection | Essential component - must be elevated[Evidence: D][16] | Used alongside C-peptide for diagnosis |
| Non-invasive option | Yes - urine C-peptide (UCPCR) available[Evidence: A][4] | No - blood sample required |
| Stimulated testing | MMTT preferred (R² = 0.96 reproducibility)[Evidence: B][6] | Can be measured during same stimulation tests |
Important: Your doctor will determine which test is appropriate for your situation. In many cases, both tests provide complementary information. For insulinoma diagnosis, research shows using all three measurements together—glucose, insulin, and C-peptide—provides the best diagnostic accuracy[Evidence: D][16].
What The Evidence Shows (And Doesn't Show)
What Research Suggests
- C-Peptide testing demonstrates excellent diagnostic accuracy for diabetes classification, with meta-analysis-level evidence showing cutoff values reliably distinguish Type 1 from Type 2 diabetes[Evidence: A][1]
- The test correctly identifies Type 1 diabetes in about 93 out of 100 cases at optimal cutoff values, with AUC values reaching 97.2%[Evidence: C][2]
- Non-invasive urine testing (UCPCR) offers comparable accuracy to blood testing for diabetes classification[Evidence: A][4]
- C-Peptide preservation correlates with better diabetes outcomes: 24.8% greater preservation equals 0.55% lower HbA1c[Evidence: A][18]
- Elevated C-Peptide in the general population predicts future Type 2 diabetes development (HR 2.35 over 7 years)[Evidence: C][20]
What's NOT Yet Proven
- Universal cutoff values: Optimal cutoffs vary by study (0.16-0.30 nmol/L for Type 1 diabetes), and standardization across laboratories remains incomplete[Evidence: D][17]
- Age-specific reference ranges: Most studies focus on adult populations; pediatric-specific cutoffs are less well-established
- Long-term monitoring protocols: Optimal frequency for serial C-Peptide testing in clinical practice not firmly established
- Wearable device validation: Continuous C-Peptide monitoring technology is preclinical; real-world validation data not yet available
Where Caution Is Needed
- Inter-laboratory variability can reach 36.6% mean bias between platforms[Evidence: C][5]. Use the same laboratory for serial monitoring.
- Glucagon stimulation testing carries significant adverse event risk (43.2% overall, with severe events in elderly patients)[Evidence: D][11][12]
- Kidney disease affects C-Peptide clearance, complicating interpretation in patients with renal impairment
- Single test results should be interpreted alongside clinical context, not in isolation
Should YOU Get This Test?
Best suited for: People with diabetes where the type is unclear, those being evaluated for insulinoma or unexplained hypoglycemia, patients on insulin therapy needing assessment of residual pancreatic function, and participants in clinical trials for diabetes treatments
Not recommended for: Routine diabetes screening (glucose/HbA1c tests are appropriate first), people without diabetes-related symptoms or conditions, regular monitoring without specific clinical indication
Realistic expectations: Results typically available within 1-3 days. Your doctor will interpret results in context of your complete clinical picture.
When to consult a professional: Before ordering this test independently; if you have questions about your results; if your diabetes type remains unclear after initial testing; if you experience unexplained hypoglycemia
Frequently Asked Questions
Can a C-Peptide test diagnose diabetes?
The C-Peptide test alone cannot diagnose diabetes. It helps classify the type of diabetes (Type 1 vs Type 2) after diabetes has been diagnosed through blood glucose or HbA1c testing. Research shows the test correctly distinguished Type 1 from Type 2 diabetes in about 8 out of 10 cases using appropriate cutoff values . If you suspect diabetes, your doctor will order glucose tests first, then may use C-Peptide testing to refine the diagnosis.
How often should I have my C-Peptide checked?
Most people don't need regular C-Peptide monitoring. The test is typically ordered once to help classify diabetes type or investigate specific conditions. Some people with Type 1 diabetes may have periodic testing to monitor remaining beta cell function, especially in clinical trial settings. Research validates C-peptide as a reliable marker for assessing treatment effectiveness . Ask your doctor if repeat testing is appropriate for your situation.
Can I use a urine test instead of a blood test?
Yes, the urine C-Peptide Creatinine Ratio (UCPCR) is a non-invasive alternative that works well for many people. Research shows the urine version correctly identified Type 1 diabetes in about 84 out of 100 cases and Type 2 diabetes in about 93 out of 100 cases . Clinical guidelines recommend UCPCR as a non-invasive alternative . Discuss with your doctor whether the urine option is appropriate for your needs.
What is LADA and how does C-Peptide help detect it?
LADA (Latent Autoimmune Diabetes in Adults) is sometimes called 'Type 1.5 diabetes.' It's an autoimmune condition like Type 1 diabetes but develops more slowly in adults. C-Peptide testing helps identify LADA by showing declining insulin production over time. Studies suggest the test correctly distinguished Type 1 diabetes from LADA in about 8 out of 10 cases using a cutoff of 0.82 ng/mL . If your doctor suspects LADA, they may combine C-Peptide testing with antibody tests.
Why might my results vary between different labs?
C-Peptide measurement is not fully standardized across all laboratory platforms. Early research suggests test results can vary significantly depending on which lab equipment is used, with differences up to 37% between some platforms . Expert consensus notes this standardization gap affects how results are interpreted . If you need to monitor C-Peptide over time, try to use the same laboratory for consistent comparisons.
Are there newer, less invasive ways to test C-Peptide?
Yes, research is exploring alternatives to traditional blood draws. Studies suggest the skin patch version (transdermal sampling) correctly detected C-peptide levels in 100 out of 100 cases when levels were at or above 200 pmol/L, with no adverse events reported . Clinical experience suggests wearable continuous monitoring devices show excellent biocompatibility and work reliably for at least 10 measurements . These technologies are still emerging but may become more widely available.
What medications or conditions can affect my C-Peptide results?
Several factors can influence results. Medications that stimulate insulin release (like sulfonylureas) may increase C-Peptide levels. Kidney disease affects C-Peptide clearance, potentially causing elevated readings even with normal pancreas function. Stress, recent meals (for non-fasting tests), and timing of blood draw can all affect results. Always inform your healthcare provider of all medications and conditions before testing so they can interpret results accurately.
What happens if my C-Peptide is very low but I was diagnosed with Type 2 diabetes?
This situation requires careful evaluation. Low C-Peptide in someone initially diagnosed with Type 2 diabetes may indicate the diagnosis needs reconsideration. You might have Type 1 diabetes that developed later in life, LADA, or advanced Type 2 diabetes where beta cells have significantly declined. Studies suggest the urine test helps identify which patients with Type 2 diabetes need insulin or other medications to help their pancreas . Your doctor may recommend antibody testing or referral to an endocrinologist.
Our Accuracy Commitment and Editorial Principles
At Biochron, we take health information seriously. Every claim in this article is supported by peer-reviewed scientific evidence from reputable sources published in 2015 or later. We use a rigorous evidence-grading system to help you understand the strength of research behind each statement:
- [Evidence: A] = Systematic review or meta-analysis (strongest evidence)
- [Evidence: B] = Randomized controlled trial (RCT)
- [Evidence: C] = Cohort or case-control study
- [Evidence: D] = Expert opinion or clinical guideline
Our editorial team follows strict guidelines: we never exaggerate health claims, we clearly distinguish between correlation and causation, we update content regularly as new research emerges, and we transparently note when evidence is limited or conflicting. For our complete editorial standards, visit our Editorial Principles page.
This article is for informational purposes only and does not constitute medical advice. Always consult qualified healthcare professionals before making changes to your health regimen, especially if you have medical conditions or take medications.
References
- 1 . The Predictive Ability of C-Peptide in Distinguishing Type 1 Diabetes From Type 2 Diabetes: A Systematic Review and Meta-Analysis, Endocrine Practice, 2023, PubMed [Evidence: A]
- 2 . The Predictive Potential of C-Peptide in Differentiating Type 1 Diabetes From Type 2 Diabetes in an Outpatient Population in Abu Dhabi, Clinical Therapeutics, 2024, PubMed [Evidence: C]
- 3 . Utility of Fasting C-Peptide for the Diagnostic Differentiation of Patients with Type 1, Type 2 Diabetes, MODY, and LADA, Life (Basel), 2024, PubMed [Evidence: C]
- 4 . Diagnostic Test Accuracy of Urine C-peptide Creatinine Ratio for the Correct Identification of the Type of Diabetes: A Systematic Review, touchREV Endocrinology, 2022, PubMed [Evidence: A]
- 5 . Comparability of C-Peptide Measurements - Current Status and Clinical Relevance, Experimental and Clinical Endocrinology & Diabetes, 2023, PubMed [Evidence: C]
- 6 . Mixed-meal tolerance test versus glucagon stimulation test for the assessment of beta-cell function in therapeutic trials in type 1 diabetes, Diabetes Care, 2008, PubMed [Evidence: B]
- 7 . Evaluation of long-term treatment effect in a type 1 diabetes intervention trial: differences after stimulation with glucagon or a mixed meal, Diabetes Care, 2014, PubMed [Evidence: B]
- 8 . Clinical Implications of Urinary C-Peptide Creatinine Ratio in Patients with Different Types of Diabetes, Journal of Diabetes Research, 2019, PubMed [Evidence: C]
- 9 . Using the Secretion Ratios of Insulin and C-peptide During the 2-h Oral Glucose Tolerance Test to Diagnose Insulinoma, Digestive Diseases and Sciences, 2021, PubMed [Evidence: C]
- 10 . A Systematic Review of the Accuracy of Insulin and C-peptide Secretion Ratios During the Oral Glucose Tolerance Test to Diagnose Insulinoma, Journal of the ASEAN Federation of Endocrine Societies, 2024, PubMed [Evidence: A]
- 11 . Safety Assessment and Potential Risks of the Glucagon Stimulation Test in the Diagnosis of Secondary Adrenal Insufficiency, Current Drug Safety, 2022, PubMed [Evidence: D]
- 12 . Potential risks of glucagon stimulation test in elderly people, Growth Hormone & IGF Research, 2015, PubMed [Evidence: D]
- 13 . Transdermal Blood Sampling for C-Peptide Is a Minimally Invasive, Reliable Alternative to Venous Sampling in Children and Adults With Type 1 Diabetes, Diabetes Care, 2024, PubMed [Evidence: C]
- 14 . A wearable device for continuous immunoassay-based monitoring of C-peptide in interstitial fluid, Science Advances, 2025, PubMed [Evidence: D]
- 15 . 2. Diagnosis and Classification of Diabetes: Standards of Care in Diabetes—2024, Diabetes Care, 2024, PubMed [Evidence: D]
- 16 . Clinical implications of various criteria for the biochemical diagnosis of insulinoma, Endocrinology and Metabolism (Seoul), 2014, PubMed [Evidence: D]
- 17 . Call for Standardization of C-Peptide Measurement, Journal of Diabetes Science and Technology, 2025, PubMed [Evidence: D]
- 18 . C-peptide and metabolic outcomes in trials of disease modifying therapy in new-onset type 1 diabetes: an individual participant meta-analysis, Lancet Diabetes & Endocrinology, 2023, PubMed [Evidence: A]
- 19 . A Practical Review of C-Peptide Testing in Diabetes, Diabetes Therapy, 2017, PubMed [Evidence: D]
- 20 . Plasma C-Peptide and Risk of Developing Type 2 Diabetes in the General Population, Journal of Clinical Medicine, 2020, PubMed [Evidence: C]
Medical Disclaimer
This content is for informational and educational purposes only. It is not intended to provide medical advice or to take the place of such advice or treatment from a personal physician. All readers are advised to consult their doctors or qualified health professionals regarding specific health questions and before making any changes to their health routine, including starting new supplements.
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