Listen to the Podcast, Episode 15: C-Peptide – What type of type 1 diabetes do you have?
For the full article: click here
Show Notes
Host: John Pemberton
Duration: ~21 minutes
Podcast: The Glucose Never Lies
00:09 – Introduction & Why This Matters
- John introduces the podcast and shares his personal background: 17 years with type 1 diabetes, dietitian, researcher, educator, and father.
- Motivation for creating clear, actionable education—especially after his son Jude tested positive for T1D antibodies.
- Acknowledges recent experience with depression and functional motor disorder and how this podcast is a way of giving back.
02:14 – What Is Brittle Diabetes?
- John revisits the term “brittle diabetes” and how he used to dismiss it.
- He now understands that not all type 1 diabetes is created equal—some people genuinely face greater biological challenges.
03:10 – The Role of Residual Insulin Function
- Introduces the concept of the honeymoon period.
- Highlights how longer C-peptide presence is linked with fewer complications and smoother glucose control.
04:37 – What Is C-Peptide and How Is It Measured?
- Explains insulin synthesis: pro-insulin → insulin + C-peptide.
- C-peptide is measured in urine or blood, often using a urinary C-peptide to creatinine ratio.
- This can now be done easily in clinic without fasting.
06:10 – Understanding C-Peptide Values
- Classifies C-peptide levels:
- High: >200 pmol/L
- Intermediate: 30–200 pmol/L
- Low: <30 pmol/L
- Non-diabetic range: ~1000–3000 pmol/L.
- Even “high” for someone with T1D is low compared to people without diabetes.
07:30 – Who Has What?
- People diagnosed under age 20 tend to have very low residual function after 15+ years.
- Nearly all children diagnosed young lose almost all residual insulin production over time.
09:11 – John’s Personal C-Peptide Story
- Diagnosed at age 27, John has 220 pmol/L, even after 10 years.
- Uses only 30 units of insulin/day.
- Reflects on bias and privilege—others have it harder.
10:20 – DCCT & Long-Term Outcomes
- In the DCCT and follow-up EDIC studies:
- High C-peptide → better HbA1c, lower fasting glucose, lower insulin dose, fewer complications.
- Dose-response relationship between residual insulin and complication risk.
11:37 – Time-in-Range & C-Peptide
- Newcastle study:
- Overnight TIR: 76% (high function) vs 50% (low)
- Post-meal TIR: 68% vs 50%
- Post-exercise TIR: 73% vs 40%
13:10 – Why Does C-Peptide Help?
- Two key reasons:
- Portal insulin clears glucose more efficiently at the liver.
- Suppression of glucagon after meals helps avoid glucose spikes.
14:01 – Using C-Peptide to Prioritize Technology
- In resource-limited settings, John’s clinic uses C-peptide to prioritize access to:
- Hybrid closed-loop systems
- GLP-1 therapies (semaglutide, tirzepatide)
- Amylin analogues
15:20 – Case Study: Athlete with Low C-Peptide
- Young triathlete with <10 pmol/L struggles with exercise management.
- Adapted nutrition strategy:
- Lower carbs before exercise, higher after.
- Careful glucose monitoring and sensor use.
- Hybrid closed-loop prioritized.
16:45 – Therapy Implications
- GLP-1 therapies may be especially helpful for low C-peptide individuals.
- Potential off-label use where supported by experienced clinicians.
- Also mentions amylin, SGLT-2s, pioglitazone as future options.
17:55 – Empathy Is Essential
- John urges both HCPs and people with diabetes to recognize that diabetes is not the same for everyone.
- Low C-peptide = greater biological burden = need for more support and less self-judgment.
18:33 – Summary & Action Steps
- Get your urinary C-peptide tested—easy and helpful.
- Interpret:
- High: >200 pmol/L
- Intermediate: 30–200
- Low: <30
- Use result to inform expectations, tech access, and individualized goals.
- Encourage realistic targets—e.g., 70% TIR may not be fair for all.
20:00 – What’s Coming Next
- Episode with Prof. Pratik Choudhary: DVLA driving guidance for T1D
- Interview with Dr. Dessi Zaharieva: Partying with T1D
- Episode with Prof. Othmar Moser: CGM + exercise
- GLP-1/GIP Deep Dive – Exploring the next wave of second-line therapies for T1D
Key links
Episode 14: Insulin Resistance and T1D
C-Peptide full article – click here
