Living with type 3c diabetes after pancreatic surgery – the practical guide

A guide for patients, families, and primary care teams from the team behind prehabforsurgery.com

If you have had your pancreas removed – in part or in full – or if you live with chronic pancreatitis, there is a strong chance that you will develop a particular form of diabetes called type 3c diabetes. It is also called pancreatogenic diabetes. It is not the same as type 1 diabetes (the autoimmune kind that often starts in childhood), and it is not the same as type 2 diabetes (the kind most often associated with weight gain and insulin resistance). It behaves differently. It needs to be managed differently. And it is widely misunderstood, including, frequently, by clinicians who are not used to seeing it.

This article is a plain-English guide to what type 3c diabetes is, why it is different, and what practical steps make day-to-day life with it easier. It is not a substitute for advice from your own diabetes team – it is a starting point for the conversations that follow.

What is type 3c diabetes?

Type 3c diabetes is diabetes that occurs because of disease, surgery, or injury to the pancreas itself. The pancreas does two completely different jobs at the same time. Its endocrine job is to produce hormones – insulin (which lowers blood sugar) and glucagon (which raises it) – both released into the bloodstream from clusters of cells called the islets of Langerhans. Its exocrine job is to produce digestive enzymes that are delivered into the gut to help break down food, particularly fats and proteins.

When the pancreas is damaged, removed, or chronically inflamed, both jobs are affected. The diabetes that results is therefore not just a problem of low insulin. It is also, very often, a problem of low glucagon, low pancreatic polypeptide, and concurrent difficulty digesting food. That combination is what makes type 3c distinct.

Who gets type 3c diabetes?

Type 3c diabetes is most commonly seen after:

• Total pancreatectomy – diabetes develops in essentially everyone unless islet auto-transplantation is performed at the time of surgery

• Distal pancreatectomy – approximately 40% of patients develop diabetes within five years

• Whipple’s procedure (pancreaticoduodenectomy) – approximately 20–30% develop new diabetes

• Chronic pancreatitis – the majority of patients develop diabetes over the course of their disease

• Pancreatic cancer – diabetes often pre-dates the diagnosis and can be triggered or worsened by the tumour itself, before any surgery

• Cystic fibrosis (cystic-fibrosis-related diabetes is a closely related condition)

• Hereditary haemochromatosis affecting the pancreas

• Pancreatic trauma – major injury to the gland

If you are reading this article because you are about to have, or have just had, pancreatic surgery – your risk depends on which operation you are having or have had, and how much functioning pancreas tissue is preserved. Your surgical team and endocrinologist should give you a clear sense of your individual risk.

Why it is different from type 1 and type 2

The most important practical difference is the loss of glucagon counter-regulation. In a healthy person, when blood sugar starts to fall, the pancreas releases glucagon, which prompts the liver to release stored glucose back into the bloodstream – a built-in safety mechanism that prevents blood sugar from dropping dangerously low. In type 1 diabetes this mechanism is largely preserved. In type 3c diabetes, particularly after surgery that removes the pancreas, the glucagon-producing alpha cells are often lost along with the insulin-producing beta cells.

The consequence is what clinicians call brittle diabetes. Blood sugar swings can be unpredictable and severe. A hypoglycaemic episode – a low blood sugar – does not self-correct the way it does in type 1 or type 2 diabetes. It can drop suddenly, dangerously, and without obvious warning, and the patient and their family need to be prepared for that.

The other key differences to know about:

• Weight: most people with type 2 diabetes are gaining weight; most people with type 3c, particularly after surgery for pancreatic cancer, are losing it or struggling to maintain it. Standard advice to “lose weight to improve your diabetes” does not apply.

• Carbohydrate absorption is unpredictable, because it depends on how well the pancreatic enzyme replacement therapy (PERT – Creon, Nutrizym, Pancrex) is timed and dosed at each meal. A meal with sub-optimal enzyme cover behaves very differently from the same meal with optimal cover.

• Insulin requirements are often lower than in type 1, but more erratic. People with type 3c can be very sensitive to small dose changes.

• Long-acting (basal) insulin is often the foundation of treatment, with short-acting insulin at meals as required. Oral diabetes medications usually have a limited role.

Standard apps and information sources designed for type 1 and type 2 diabetes do not always translate well. Some of the carb-counting and dose-calculation tools assume a normal pancreatic response that you no longer have. If something you read or use does not seem to fit your experience, that is not your fault – it is the tool, not you.

The four practical challenges – and what to do about each

1. Brittle hypoglycaemia

The single biggest difference, and the most dangerous one. The absence of a normal glucagon response means that low blood sugars can become severe quickly. The best protections are anticipation and tools:

• Continuous glucose monitoring (CGM) – devices like the Dexcom or FreeStyle Libre – is, in our practice, the single most valuable intervention. Continuous data, audible low-glucose alerts, and trend arrows mean you see a drop coming before it becomes a crisis. Most insurers and Long-Term Illness Schemes will fund CGM for people with type 3c diabetes; ask your team.

• Glucagon emergency kit – every household should have one, every family member should know how to use it, and the patient should always carry one when travelling. The two formats currently available are nasal glucagon (Baqsimi) and pre-filled injectors (Gvoke, GlucaGen). Discuss the right format for you with your team.

• Fast-acting glucose – always within reach. Glucose tablets, juice cartons, jelly babies – whatever works for you, in every bag, every car, every bedside table.

• Hypoglycaemia unawareness – over time, repeated lows can blunt your ability to feel the warning symptoms (sweating, shaking, racing heart). If this starts to happen, it is a clinical red flag. Tell your team immediately. Avoiding any low for several weeks can sometimes restore awareness.

2. PERT (pancreatic enzyme replacement) and the timing of meals

PERT – Creon being the most commonly prescribed – replaces the digestive enzymes the pancreas would normally produce. The challenge is that the same meal can produce a very different blood sugar response depending on whether the enzyme dose was right and whether the timing was right.

• Take PERT at the start of the meal – not before, not after. Capsules need to mix with food in the stomach to work; taken too early or too late, much of the dose is wasted.

• For a long meal (longer than 20-30 minutes), split the dose – half at the start, half halfway through.

• Snacks need PERT too – even small ones containing fat or protein. A small snack-dose (typically 25,000-50,000 units lipase) covers most snacks.

• Do not chew capsules. Do not take with very hot or alkaline drinks (the enteric coating breaks down and the enzymes are destroyed before they reach the gut).

• Carb counting becomes unreliable when PERT is under-dosed – the body cannot absorb the carbs predictably, and the insulin you have given is then mismatched to what is actually being absorbed.

• Travel: always carry PERT in hand luggage. Heat damages it, and lost luggage means several days of malabsorption.

For a full practical guide to PERT timing and dosing, see [PERT — the practical patient guide →]

3. Weight, nutrition, and fat intolerance

People with type 3c diabetes often struggle to maintain weight, and the advice they hear (“low-fat diet, watch the carbs”) is often the opposite of what their body needs.

• Aim for a high-protein, normal-to-moderate-fat diet, with PERT properly dosed against the fat content of each meal. Restricting fat just for fat’s sake usually makes things worse – it removes a key calorie source without solving the underlying enzyme problem.

• Frequent small meals are usually better tolerated than three large ones.

• If you have steatorrhoea (fatty, foul-smelling, hard-to-flush stools), that is a sign the enzyme dose is too low for what you are eating. Tell your dietitian – the dose needs to go up, not the food intake to go down.

• Fat-soluble vitamin levels (A, D, E, K) should be checked at least annually – deficiency is common and quietly causes problems if missed.

• Calcium and magnesium levels often need attention too, particularly after total pancreatectomy.

4. Exercise and sick days

Both of these change the rules of blood sugar control, and need a plan in advance.

• Exercise – especially moderate-to-intense exercise – can cause delayed hypoglycaemia, sometimes hours later, even into the next morning. CGM, a snack before or during, and a reduced basal insulin dose for the evening may all be needed. Discuss a specific exercise plan with your team rather than guessing.

• Illness – particularly anything affecting the gut (vomiting, diarrhoea) – disrupts both PERT absorption and insulin sensitivity simultaneously. Sick-day rules for type 3c need to address both: how to dose PERT when not eating normally, how to adjust insulin when intake is reduced, and when to seek help. Ask your team for written sick-day rules and keep them somewhere accessible.

• Surgery, infection, steroids, or any major medical event will change insulin requirements quickly. Stay in close touch with your diabetes team during any such episode.

• If your surgery included splenectomy, also see [Vaccines and antibiotics after splenectomy]

A practical daily routine that works for most people

Every person is different and the following is a starting point, not a prescription. Adapt with your team.

• On waking – check glucose (or look at CGM), take basal insulin if scheduled.

• Breakfast – start with PERT capsules; eat the meal within 15–20 minutes; take short-acting insulin per your meal plan based on actual carbs.

• Mid-morning – small protein-containing snack with snack-dose PERT if tolerated.

• Lunch – repeat the PERT-and-insulin pattern; if blood sugar is trending low on CGM, eat first, dose later.

• Afternoon – small snack if needed; review trends on CGM.

• Pre-dinner – assess the day so far and plan the evening accordingly. If you have exercised, reduce the evening basal insulin per your team’s advice.

• Dinner – PERT, insulin, eat. Avoid very late large meals if possible.

• Bedtime – glucose check (CGM trend); have fast-acting glucose at the bedside; ensure glucagon kit is in the bedroom; family member knows where it is.

• Sleep – set CGM low-glucose alarm; the alarm is what protects you overnight.

Tools – what helps and what does not yet exist

Continuous glucose monitoring is the single most useful technology currently available for type 3c. Insulin pumps can help in selected people but are not always necessary, particularly if basal needs are modest. The Diabetes UK and ADA general-diabetes apps are useful for logging insulin and meals, but they are not built for the PERT-coordinated pattern of type 3c. At the time of writing there is no widely-used app that handles both PERT timing and carb counting in a way that is purpose-built for type 3c – this is a real gap, and an area we are actively working on.

When to seek urgent help

• Recurrent or severe hypoglycaemia – particularly if losing awareness of warning symptoms

• Unexplained weight loss continuing despite eating

• Worsening steatorrhoea (fatty stools) – a sign PERT dose needs review

• Vomiting or diarrhoea lasting more than 24 hours – risk of ketoacidosis and PERT/insulin balance disruption

• Blood sugars persistently above 15 mmol/L (270 mg/dL) for more than a few hours with ketones

• New severe abdominal pain – particularly after recent pancreatic surgery

• Any loss of consciousness or seizure – emergency, glucagon if available, ambulance

Long-term outlook

Many people live well with type 3c diabetes for decades. The keys are early recognition that this is a distinct condition needing distinct management, a diabetes team familiar with type 3c (not all are), CGM as a daily tool, careful PERT discipline, and a clear written plan for emergencies. The brittleness is real but manageable. Hypoglycaemia awareness training, structured education programmes (like DAFNE adapted for type 3c), and the support of patient communities all help.

Long-term complications of diabetes – eye, kidney, nerve and vascular complications – apply to type 3c as they do to type 1 and type 2. Annual screening for these is just as important. If you are not currently attending an annual diabetes review, ask your GP to refer you.

Resources and next steps

• Diabetes Ireland – diabetesireland.ie – Irish patient charity; has Type 3c information requests in their queue but coverage is currently limited.

• Diabetes UK – diabetes.org.uk – has a small but growing Type 3c information section.

• National Pancreas Foundation (US) – pancreasfoundation.org – patient-focused resources including chronic pancreatitis and post-surgical diabetes.

• Mission: Cure – mission-cure.org – particularly active community for chronic pancreatitis patients.

• Pancreatic Cancer UK – pancreaticcancer.org.uk – practical guides for post-surgical recovery including diabetes.

• Patient communities – there are active Facebook groups (“Whipple Procedure Support”, various pancreatic cancer support groups) and a Reddit community (r/ChronicPancreatitis) where people compare day-to-day strategies.

Evidence base

Key sources informing this article:

• Hart PA, Bellin MD, Andersen DK et al. Type 3c (pancreatogenic) diabetes mellitus secondary to chronic pancreatitis and pancreatic cancer. Lancet Gastroenterol Hepatol 2016;1(3):226–37.

• Cui Y, Andersen DK. Pancreatogenic diabetes: special considerations for management. Pancreatology 2011;11(3):279–94.

• Petrov MS, Yadav D. Global epidemiology and holistic prevention of pancreatitis. Nat Rev Gastroenterol Hepatol 2019;16(3):175–84.

• Cuthbertson DJ, Bellin MD et al. Glucose-lowering therapies for the treatment of type 3c diabetes. Diabetes Obes Metab 2021.

• American Diabetes Association. Standards of Care in Diabetes – 2024. Diabetes Care 2024 (Type 3c classification, sections on diabetes secondary to other conditions).

• Royal College of Physicians of Ireland / Diabetes Ireland – current Irish guidelines on management of secondary diabetes.

A final word

Type 3c diabetes is not a punishment, a failure of diet, or a moral problem. It is a mechanical consequence of damage to a single organ that does two important jobs at once. The condition is manageable. The tools are there. The information is improving. And, increasingly, the patient community is being heard. If you are recently diagnosed, give yourself time to learn the patterns of your own body. If you have lived with this for years, the principles in this article will be familiar – but the tools, particularly CGM, may have moved on since you were first taught.

If anything in this article does not match what your own team is telling you, your team’s advice for your particular situation takes precedence. This is a general guide; your care is specific.

Reviewed by Mr Tom Gallagher, Consultant HPB Surgeon, St Vincent’s Healthcare Group, Dublin. Last updated 26 May 2026.