Type 3c Diabetes Symptoms, Signs, Diagnosis, and Treatment

Type 3c diabetes

Diabetes is commonly classified as T1DM, T2DM, GDM, and Specific types of diabetes. Among the specific types, Type 3c diabetes is one type that is not very uncommon.

Type 3c diabetes or pancreatogenic diabetes is the type of diabetes that commonly occur in patients who have pancreatic cancer or that develop after pancreatitis.

The prevalence of type 3c diabetes is very high. It is estimated to affect about 9% of all individuals with diabetes.

Prevalence of Diabetes [Ref]

Type 1 Diabetes23.1%
Type 2 Diabetes67.7%
Type 3c Diabetes9.2%

What is Type 3c Diabetes?

Most people are aware that type 1 diabetes is an autoimmune disease that is caused by the destruction of beta cells leading to absolute insulin deficiency. Type 2 is a spectrum disease caused due to insulin resistance.

Type 3c diabetes is the type of diabetes that occurs when the pancreas stops producing the hormone insulin.

This can be due to any reason, an underlying disease, or damage to the pancreas. It can also happen in people who have undergone pancreatectomy (surgical removal of the pancreas).

This causes insufficient levels of insulin in the body resulting in symptoms of diabetes.

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Causes of Type 3C Diabetes:

Type 3c diabetes mellitus is caused by an impairment in the endocrine function of the pancreas due to some exocrine damage. This damage can be caused due to conditions such as:

  • Cystic fibrosis
  • Pancreatitis (acute or chronic)
  • Hemochromatosis
  • Pancreatic cancer
  • Pancreatectomy

Any of these conditions damage the pancreas and insulin production is stopped. In type 3c diabetes, your pancreas also stops producing enzymes for digestion.

Type 3c diabetes can only be caused by a pancreas-related illness or conditions as mentioned in the table below [Ref]:

Causes of Type 3c Diabetes

Chronic Pancreatitis79%
Pancreatic Cancer8%
Hereditary hemochromatosis7%
Cystic fibrosis4%
Post-pancreatic resection2%

Prevalence of Type 3C Diabetes:

According to studies, 8% of all diabetes patients have Type 3c diabetes. The overall occurrence ranges from 5% to 80%. [Ref]

It is highly prevalent in:

  • People who have undergone surgical removal of the pancreas
  • Smokers
  • Presence of Pancreatic calcifications
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How does type 3c diabetes develop?

When the pancreas is damaged, an exocrine insufficiency often occurs first which is then preceded by an endocrine insufficiency.

Patients of type 3c diabetes first develop abdominal pain, steatorrhea, and glucose intolerance.

Changes to glucose metabolism are slow and often asymptomatic. Later, the disease progresses to diabetes marked by frequent episodes of hypoglycemia.

Type 3c Diabetes Symptoms and Signs:

If you have type 3c, your pancreas may not be able to provide you with the nutrients you require to digest your food.

This is known as pancreatic exocrine insufficiency (PEI), and it indicates that your pancreas is not functioning properly.

Some of the symptoms of type 3c diabetes are:

  • Weight loss
  • Stomach pain
  • Persistent fatigue
  • Diarrhea
  • Fatty stools
  • Hypoglycemia

Other symptoms of diabetes are the same as Type 1 or Type 2 Diabetes. However, compared to patients with Type 1 Diabetes, these patients usually do not develop DKA (diabetic ketoacidosis).

Their blood sugars may be as high as above 500 mg/dl but they do not develop DKA as there is concomitant glucagon deficiency as well.

Unlike T2DM, these patients are thin and lean and usually require insulin for hyperglycemia.

In addition, individuals with T3cDM may also have symptoms of the underlying disease of pancreatic dysfunction such as arthritis and jaundice in hemochromatosis, chronic cough in cystic fibrosis, persistent vomiting, weight loss, and jaundice in pancreatic cancer.

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How to Diagnose Type 3c Diabetes?

It is often difficult to diagnose type 3c diabetes because of the similar symptoms with other forms of diabetes. Some tests to diagnose type 3cDM are:

  • Fasting blood glucose levels
  • HbA1c
  • Pancreatic pathological imaging
  • Tests for detection of T1DM-related autoantibodies
  • Pancreatic polypeptide test
  • Serum levels of fat-soluble vitamins

The suggested diagnostic criteria is presented here in a table format:



Major Criteria

Exocrine Pancreatic InsufficiencyDetermined by monoclonal fecal elastase-1 testing or direct function tests.
Consistent Pancreatic Abnormalities on ImagingIdentified through endoscopic ultrasound, MRI, or CT scan.
Absence of Related Autoimmune MarkersAbsence of markers typically associated with Type 1 diabetes, such as autoantibodies (e.g., GAD antibodies).

Minor Criteria

Impaired β-Cell FunctionMeasured by homoeostatic model assessment for β-cell function, C-peptide, or glucose concentrations.
Absence of Insulin ResistanceAs defined by homoeostatic model assessment for insulin resistance.
Impaired Incretin SecretionIncluding glucagon-like peptide-1 (GLP-1) or pancreatic polypeptide, or both.
Low Serum Concentrations of Lipid-Soluble VitaminsSuch as Vitamins A, D, E, and K.

Here is a basic comparison of type 1, type 2, and type 3 c diabetes.


Type 1

Type 2

Type 3c

Insulin levelsLowHighLow
Glucagon levelsNormal to highNormal to highLow
Age of onsetChildhood/ adolescenceAdulthood (4th or 5th decade of life)Adulthood (usually 3rd decade of life)
Pancreatic polypeptideLow or absentNormalDecreased


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Complications of Type 3c Diabetes

T3cDM has the same complications as other forms of diabetes such as

Other complications associated with T3c DM are:

  • Undernutrition
  • Chronic malabsorption

Patients with T3cDM can develop all the complications of T1DM and T2DM except they are less likely to develop DKA (diabetic ketoacidosis).

DKA is less common because these patients lack exocrine hormones as well. One important hormone that plays a key role in the development of DKA is Glucagon.

When glucagon is deficient, the person with T3cDM may not be able to metabolize fatty acids into ketone bodies which is the major pathophysiologic mechanism of DKA.

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Treatment of Type 3C Diabetes:

Treatment of type 3c diabetes is based on pharmacological treatment and medical nutrition therapy along with necessary lifestyle modifications.

Pharmacological Treatment:

Pharmacological treatment involves the treatment of hyperglycemia with metformin or exogenous insulin. Patients with chronic pancreatitis usually require exogenous insulin to control blood glucose levels.

The main aim of this treatment is to achieve HbA1c levels of less than 7%. Maintaining this level also reduces the risk of the associated macro and microvascular complications.

Treatment with pancreatic enzymes, as previously discussed, is also important for maintaining incretin hormone secretion in patients with exocrine insufficiency, where their use is associated with improved glucose tolerance during meal ingestion.

Nutritional management:

Medical nutrition therapy is essential to manage conditions such as:

  • Chronic undernutrition
  • Malabsorption
  • Steatorrhea
  • Meal-induced hyperglycemia

The initial therapy should begin with the correction of lifestyle factors that contribute to hyperglycemia and malignancy, such as reinforcing weight loss for the obese, daily exercise, and carbohydrate restriction, as well as recommending abstinence from alcohol and smoking cessation.

Although ADA has not provided any specific guidelines for type 3c diabetes, here are some key recommendations:

  • A regular meal plan should be provided, with specified, controlled amounts of starchy carbohydrates.
  • Blood glucose levels should be checked on a regular basis with self-monitoring before and after meals especially recommended for those on intensive insulin regimens.
  • Taking small frequent meals helps in regulating blood glucose levels
  • Meals should be high in fiber and must include carbohydrates that have a low glycemic index
  • Oral pancreatic enzyme replacement therapy should be done to reduce the symptoms of steatorrhea and fat malabsorption.
  • Intake of high GI/ high sugar food should be avoided.
  • A low-fat diet should be followed
  • Fat malabsorption might lead to a deficiency of vitamin D which might cause symptoms of osteoporosis, this deficiency must be cured with proper supplementation of vitamin D

Alcohol and Smoking

Alcohol and smoking are two modifiable contributors to pancreatitis. Abstinence from alcohol and quitting smoking are highly recommended because both contribute to the progression of pancreatic inflammation and tissue fibrosis.

Refraining from alcohol is also beneficial in the management of diabetes because alcohol inhibits the production of glucose from the liver causing hypoglycemia. This condition is more prevalent in people on insulin therapy.

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What do you think?

Written by Dr. Ahmed

I am Dr. Ahmed (MBBS; FCPS Medicine), an Internist and a practicing physician. I am in the medical field for over fifteen years working in one of the busiest hospitals and writing medical posts for over 5 years.

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