Am I Type 3c or Type 2? How to Tell the Difference

By Leon Wilkinson, Type 3c patient and developer of GlycoTrace · Updated June 2026

Photo: Thirunavukkarasye-Raveendran / Wikimedia Commons, CC BY 4.0

This article is part of our complete guide to Type 3c diabetes, which covers what it is, its causes, diagnosis and day-to-day management.

Why this misdiagnosis is so common

When I was first diagnosed with diabetes after pancreatitis, I was told I had Type 2. My GP did not mention Type 3c. I spent over a year on medication that was not fully working before a specialist reviewed my case and gave me the right diagnosis.

This is not unusual. A study published in Diabetes Care found that up to 80% of Type 3c diabetes cases are initially classified as Type 2. There are a few reasons for this:

• The blood sugar readings look similar at the point of diagnosis
• Many GPs are not familiar with Type 3c as a distinct category
• There is no single definitive test, so diagnosis requires joining up different pieces of information
• Type 3c is relatively rare compared to Type 1 and Type 2, so it is often not the first thing a doctor thinks of

Misdiagnosis matters because the two conditions are managed differently. If you have Type 3c and are being treated as Type 2, you may be missing insulin when you need it, not taking PERT (enzyme replacement therapy), and not getting monitoring appropriate to your actual glucose patterns.

Type 3c vs Type 2: the key differences

Clues that your diabetes might be Type 3c

These are not diagnostic criteria on their own, but they are the questions worth asking if you are uncertain about your diagnosis:

• You had pancreatitis before or around the time of diagnosis, whether acute or chronic
• You have had pancreatic surgery, a Whipple procedure, distal pancreatectomy, or total pancreatectomy
• You have exocrine pancreatic insufficiency (EPI) — greasy or floating stools, bloating, difficulty digesting fatty foods
• Standard Type 2 treatment is not working well, even with good compliance
• You experience frequent and unexpected hypos, including overnight, without obvious cause
• You have lost weight since your diagnosis, even though Type 2 patients often struggle with weight gain
• Your blood sugar is very variable, harder to control than the textbooks suggest for Type 2
• Your diabetes was diagnosed within a few years of a pancreatic event or diagnosis

How Type 3c is actually diagnosed

There is no single blood test that confirms Type 3c. Diagnosis is made by combining several pieces of information:

1. History of pancreatic disease. This is the most important factor. If you have documented pancreatitis, pancreatic surgery, or another pancreatic condition, Type 3c should be on the table.

2. Fecal elastase-1 test. This stool test measures whether your pancreas is producing enough digestive enzymes. A low result indicates exocrine pancreatic insufficiency, which is present in the majority of Type 3c cases and essentially absent in Type 2. It is a cheap, non-invasive test that your GP can order. If you have not had one, ask for it.

3. Ruling out Type 1. Type 1 is caused by autoimmune destruction of beta cells. A blood test for autoantibodies (GAD-65, IA-2, ZnT8) distinguishes Type 1 from Type 3c. Both can require insulin, but Type 1 is autoimmune; Type 3c is structural.

4. Pancreatic imaging. A CT or MRI scan may show scarring, calcifications, duct dilation, or reduced pancreatic volume consistent with chronic pancreatitis or other structural damage. This supports the diagnosis but is not always present.

5. C-peptide test. This measures how much insulin your pancreas is producing. A low C-peptide with a history of pancreatic disease suggests Type 3c. A normal or high C-peptide is more consistent with Type 2.

What to say to your GP or specialist

If you think you may have been misdiagnosed, you do not need to be confrontational. A straightforward approach works well:

"I had pancreatitis in [year]. I've read that diabetes following pancreatitis can be Type 3c rather than Type 2, and that the management is different. Could we check whether my diagnosis has taken that into account? I'd like to know whether a fecal elastase test and C-peptide test would be appropriate."

If your GP is not familiar with Type 3c, you can point them to the NICE guidelines on chronic pancreatitis, the Pancreatic Cancer Action Network resources, or ask for a referral to an endocrinologist with experience in pancreatic conditions.

Why tracking matters more if you have Type 3c

Once you have the right diagnosis, glucose tracking becomes especially important in Type 3c for two reasons.

First, your glucose patterns are harder to predict. Without glucagon as a safety net, hypos can develop quickly. A CGM gives you early warning before a reading drops to a dangerous level, and the trend arrow tells you whether you are falling fast or slowly.

Second, your readings after meals depend on multiple interacting factors: what you ate, how much fat was in the meal, whether your PERT dose was right, whether you took insulin at the right time. Understanding those interactions takes time and data. Logging meals and enzyme doses alongside glucose gives you that data in one place, rather than trying to recall it from memory at a clinic appointment.

I built GlycoTrace because none of the existing apps let me do this. It is free, available on Android, and connects to FreeStyle Libre. You can read more about what to look for in a Type 3c diabetes app here.

Common questions

Related reading

• Best app for Type 3c diabetes: what actually works in 2026
• GLP-1 drugs and Type 3c diabetes: should you take Ozempic?
• Why is my blood sugar unpredictable after pancreatitis?
• CGM for Type 3c diabetes: what the research says