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Treatment research project

Can measuring insulin release help correctly diagnose diabetes?

The symptoms of type 1 and type 2 diabetes can overlap in adults, which leads to misdiagnoses. Around a third of adults with type 1 diabetes are initially incorrectly diagnosed with type 2 diabetes, and a sixth of adults diagnosed with type 1 diabetes actually have type 2. Dr Nicholas Thomas wants to find out whether a simple test to measure someone’s C-peptide levels can help prevent misdiagnoses.
Content last reviewed and updated: 07.07.2023

Dr Nicholas Thomas

What is C-peptide testing?

C-peptide levels are a measure of how much insulin someone can release. C-peptide tests cost just £10 and can confirm whether someone has type 1 or type 2 diabetes. At diagnosis, the amount of insulin people with type 1 and 2 can release often overlaps. But after three years, people with type 1 should have much lower C-peptide levels than people with type 2. So, the best time to do a C-peptide test is three years after diabetes diagnosis.

Why is JDRF funding this project?

Correctly identifying type 1 diabetes is vital for appropriate treatment and education. But people misdiagnosed with a different type of diabetes than the one they have may receive the wrong treatment. Routinely measuring C-peptide levels of people treated with insulin after three years may identify misdiagnoses. This would allow them to start receiving the appropriate education, technology, and treatment for them.

Nick’s previous research

Nick previously recruited 1800 people who had been diagnosed with type 1 or 2 diabetes for less than a year. The participants are all adults aged 18 – 90 years old. He monitored these participants and after three years 850 of these people were being treated with insulin. These participants then did a C-peptide test.

What will Nick do in this research project?

Now, Nick will follow up these 850 people to see how their C-peptide test impacted their healthcare and quality of life. He will find out how many people’s diagnosis and/or treatment changed following their C-peptide test, and if this change improved their blood glucose levels. This research will help Nick determine if everyone suspected to have type 1 diabetes should have routine C-peptide tests three years after diagnosis.

How will this project help people with type 1?

This project will help reduce misdiagnoses and ensure people with diabetes are given the right treatment and technologies for them. People diagnosed with insulin-dependent type 2 diabetes are given fixed insulin doses and medication.

If they are then found to have type 1, they can begin standard type 1 diabetes treatment. This means regularly or continuously measuring their blood glucose levels, carb-counting and giving themselves varying amounts of insulin by injecting or using an insulin pump. This should help them achieve more stable glucose levels, reduce their hypoglycaemia, and may also help limit any diabetes-related health complications.

Is JDRF funding any other research like this?

Nick’s project focuses on helping everyone with type 1 diabetes get the correct diagnosis. We are funding another study which is diagnosing people with type 1 diabetes as early as possible – before they are even experiencing symptoms. The study is called EarLy Surveillance for Autoimmune diabetes (ELSA) and you can read more about ELSA in our news story.

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