Fibrocalculous pancreatic diabetes (FCPD): what is it?

Most people with diabetes in India have type 2 diabetes. A smaller group has a very different form, caused not by insulin resistance or by the immune system, but by damage to the pancreas itself. One of these forms is fibrocalculous pancreatic diabetes, or FCPD. It was first described in detail from India, particularly Kerala, and Indian doctors have done much of the research on it.

What is FCPD?

The pancreas has two jobs. It makes digestive juices that help break down food, and it makes insulin to control blood sugar.

In FCPD, the pancreas is scarred over many years by a condition called tropical chronic pancreatitis (also called tropical calcific pancreatitis). The scarring is “fibro”. Stones of calcium form inside the pancreas ducts, which is “calculous”. Over time the insulin-making cells are lost, and diabetes develops.

Doctors now group FCPD with other forms of diabetes that come from disease of the pancreas, sometimes called type 3c diabetes or pancreatogenic diabetes. You may see the older label “malnutrition-related diabetes” in old records. That term is no longer used.

How is it different from alcohol-related pancreatitis?

Chronic pancreatitis in adults is often linked to heavy alcohol use. Tropical chronic pancreatitis is different:

• It is not caused by alcohol.
• It usually starts in childhood or the teenage years.
• Stones in the pancreas tend to be large and dense.
• It is seen mostly in people from tropical countries such as India, Bangladesh and Sri Lanka.

What causes tropical chronic pancreatitis?

The exact cause is still not fully known. Older theories blamed poor nutrition and eating cassava (tapioca), a staple in parts of South India. Most experts no longer believe these are the main causes. Malnutrition is now thought to be mainly a result of the disease, since a damaged pancreas cannot digest food well.

Current evidence points to a genetic tendency, especially changes in a gene called SPINK1 that normally protects the pancreas from its own digestive juices, combined with yet-unknown environmental triggers. Interestingly, the condition appears to be becoming less common in India in recent decades.

What are the typical symptoms?

Doctors describe a classic sequence, though not everyone follows it:

1. Tummy pain in childhood, usually in the upper abdomen and often going through to the back.
2. Stones in the pancreas, found in the teenage years or early adulthood, sometimes by chance on an X-ray or scan.
3. Diabetes in young adulthood, often before the age of 30 to 40.

Other common features:

• Being lean or underweight, unlike most people with type 2 diabetes.
• Steatorrhoea: pale, oily, bulky stools that float and are hard to flush, because fat is not being digested.
• Weight loss despite a good appetite.

Some people never had much pain, and the diabetes is the first sign.

Why do people with FCPD rarely get ketoacidosis?

Many people with FCPD have high sugar and need insulin, like people with type 1 diabetes. But unlike type 1 diabetes, they rarely develop diabetic ketoacidosis (DKA), a dangerous build-up of acids in the blood. The likely reasons are that their pancreas still makes a small amount of insulin, and that they have less body fat available to break down into ketones. Rarely is not never, so severe illness still needs urgent care.

How is FCPD diagnosed?

Your doctor will look for:

• Diabetes, confirmed with the usual blood tests such as fasting sugar and HbA1c.
• Evidence of pancreas damage, such as stones or widened ducts on an X-ray, ultrasound or CT scan. On a plain X-ray, the stones show up as white specks near the upper lumbar spine.
• Poor digestive function, for example a low stool elastase test.
• No other cause of pancreatitis, such as alcohol, high calcium or very high triglycerides.

A C-peptide blood test, which shows how much insulin your pancreas still makes, can help. Many people with FCPD are first thought to have type 1 or type 2 diabetes, so the right label can take time.

How is FCPD treated?

Treatment has four parts, and your endocrinologist and gastroenterologist will plan it with you.

1. Controlling blood sugar. Most people need insulin. Some with milder disease manage on tablets for a time. Certain diabetes medicines are generally avoided or used with caution because of the damaged pancreas, so your doctor will choose carefully. Low sugar episodes can be more common in FCPD, because the pancreas also makes less of the hormone that raises sugar, and because food absorption is unpredictable. Regular meals and home sugar checks help. You can use the HbA1c to average glucose converter to understand your HbA1c.

2. Digestive enzymes. Pancreatic enzyme capsules, taken with meals as prescribed, replace the missing digestive juices. They reduce oily stools, help weight gain and can make sugar control smoother.

3. Nutrition. A balanced diet with enough calories and protein is important, since many people are underweight. Doctors may also check and replace the fat-soluble vitamins A, D, E and K and look for weak bones.

4. Managing pain and stones. Pain may be managed with medicines. When pain is severe or ducts are blocked, endoscopic procedures to remove stones, shock-wave treatment, or surgery may be advised.

What are the long-term risks?

• Diabetes complications affecting the eyes, kidneys and nerves can occur, just as in other types of diabetes, so yearly screening is needed.
• Pancreatic cancer. People with FCPD have a much higher risk of pancreatic cancer than the general population. This is one of the most important reasons for regular follow-up. New pain, weight loss or jaundice should be checked quickly.
• Weak bones from poor absorption of vitamin D and calcium.

FCPD cannot go into remission the way some type 2 diabetes can, because the insulin-making cells are lost. Read about diabetes remission and who it applies to.

What should you ask your doctor?

• Is my diabetes definitely FCPD, or another type?
• Do I need enzyme capsules, and how should they fit around my meals?
• How often should I have scans of my pancreas?
• What should I do if I get low sugar episodes?

FCPD is uncommon and needs a team approach. An endocrinologist can coordinate your care; see who an endocrinologist is, or book a consultation.