The Glucose Never Lies®
The Glucose Never Lies® Podcast is brought to you by John Pemberton, together with Chad, his innovation partner who helps turn ideas into production. Behind the scenes, the creative team brings research, stories, and lived experiences of type 1 diabetes into an accessible format — combining science, storytelling, and strategy to help people live better with diabetes.
About Me
I’m John Pemberton — dad, husband, diabetes dietitian, researcher, and someone who’s lived with type 1 diabetes since 2008.
This podcast is my way of giving back. When my son Jude tested positive for type 1 diabetes antibodies, everything changed. I knew I had to act quickly and create a resource that was both comprehensive and easy to understand, so that anyone who might one day help manage his diabetes would feel supported. That’s how The Glucose Never Lies started — as an education platform to support my son’s future care.
Fortunately, his confirmatory test came back negative — but this doesn’t rule him, or my daughter, out. And since I was diagnosed at 27, I know just how real that risk can be.
The last two years have been the hardest of my life — battling depression, a functional motor disorder, and finally receiving an ADHD diagnosis. My journey back to health was made possible by the incredible support of my family, friends, and the wider diabetes community.
That experience taught me the power of giving. Written guides don’t work for everyone, but podcasts bring information to life in a real and relatable way. So that’s why I started this podcast — to make diabetes management engaging, practical, and fun.
I’ve been fortunate to work alongside some of the world’s leading researchers and thought leaders in type 1 diabetes, and I bring them onto the show to share their research, their stories, and their innovations.
You’ll also hear from people living with type 1 diabetes who are doing amazing things, and from advocates and clinicians shaping the future of diabetes care.
Here you’ll find guides, reflections, and conversations on everything from partying with T1D, continuous glucose monitoring and automated insulin delivery, to nutrition, exercise, insulin resistance, and childhood diabetes care.
Just to be clear — this podcast is for educational and informational purposes only. It’s not medical advice. Always consult your healthcare team before making any changes to your management.
I’m glad you’re here. Let’s get started.
The Glucose Never Lies®
11: CGM Accuracy (Part 2): Understanding MARD, 20/20, 40/40, and Error Grids.
In this episode of the Glucose Never Lies podcast, hosts John Pemberton and Louise discuss the intricacies of diabetes management, focusing on continuous glucose monitoring (CGM) systems. They explore the importance of CGM accuracy, the standards set by regulatory bodies, and the significance of testing conditions in evaluating these devices. The conversation delves into various metrics used to assess CGM performance, including MARD, 20/20 and 40/40 agreement rates, and highlights the need for robust testing against capillary glucose to ensure effective diabetes management. The episode emphasises the importance of transparency in CGM studies and the future directions for standardizing testing protocols.
takeaways
- CGM systems are crucial for real-time glucose monitoring.
- FDA standards are currently the highest for CGM performance.
- CE marking does not guarantee device accuracy or reliability.
- Testing conditions significantly impact CGM accuracy results.
- The 20/20 standard indicates no risk for insulin dosing decisions.
- The 40/40 metric identifies high-risk readings in CGM data.
- Robust testing against capillary glucose is essential for accuracy.
- Standardization in CGM testing is needed for better diabetes management.
- Transparency in CGM studies is vital for healthcare professionals and patients.
00:00
Introduction to Diabetes Management and Podcast Goals
02:07
Understanding Continuous Glucose Monitoring (CGM) Systems
06:08
Evaluating CGM Accuracy and Performance Standards
10:09
The Importance of Testing Conditions in CGM Studies
14:13
Metrics for Assessing CGM Accuracy
18:03
Comparing CGM Systems Against Capillary Glucose
22:02
Future Directions for CGM Testing and Standards
Key Resources
CGM Series: Assessing CGM Accuracy Performance
Chart for CGM Devices (From May 2025): DSN Forum
Tim Street @ Diabettech
