Cystic Fibrosis-Related Diabetes (CFRD)

The most common types of diabetes are type 1 and type 2 diabetes. CFRD has some features that are common in both. Type 1 diabetes used to be called insulin-dependent or juvenile-onset diabetes. It occurs most often in childhood. People with type diabetes can’t make any insulin, so they must take insulin to stay alive. This is why type diabetes is often called “insulin-dependent diabetes.” People with type diabetes who miss insulin doses get very sick and can get ketoacidosis (a life-threatening change in blood acidity). Type 2 diabetes used to be called non–insulin dependent or adult-onset diabetes. It is caused by the lack of a normal response to insulin in addition to not making enough insulin. This type of diabetes occurs most often in overweight people over the age of 0. People with type 2 diabetes don’t often get ketoacidosis, but they can get very sick when their blood sugars are too high. People with type 2 diabetes do not always need insulin to manage their diabetes. Some use insulin. Some take pills. Most are told to lose weight. Some manage type 2 diabetes through diet and exercise alone.


T1DM: The body cannot make insulin

T2DM: The body lacks normal responses to insulin and does not make enough insulin

CFRD: The body cannot make or use insulin

Causes of CFRD

CFRD is unique, though it shares features with both type and type 2 diabetes. As in type diabetes, the pancreas does not make enough insulin. Thus, people with CF have insulin deficiency. This is likely due to scars in the pancreas because of thick mucus. Most people with CF make less insulin than normal, though not all with CF get diabetes. Some people with CF get diabetes because they may have insulin resistance. This means that the cells in the body do not use insulin the right way so more insulin is needed to change food into fuel and keep blood sugars in the normal range. Because many with CF have both insulin deficiency and insulin resistance, more people with CF get diabetes than do people without CF. Even when people with CF are not acutely ill, their chronic underlying infections can cause insulin resistance. A third cause of insulin resistance is higher than normal cortisol levels. The hormone cortisol is a steroid. It is made in the adrenal glands. Our bodies make higher than normal cortisol levels in response to stress. High cortisol levels get in the way of insulin’s action. Steroid-containing drugs (called corticosteroids) can also increase cortisol levels. These drugs are sometimes needed to treat lung disease. When taken, they can, for a little while, worsen blood sugar control. In people with CF who do not have diabetes, using corticosteroids can give them diabetes for a little while during and after corticosteroid treatment. People can have CFRD only sometimes (intermittent CFRD) or always (chronic CFRD). If you have intermittent CFRD, you may only need to take insulin when sick or during steroid treatment. If you have chronic CFRD, you need insulin treatment at all times to prevent high blood sugar levels. Although CFRD is unique from type or type 2 diabetes, the problems caused by diabetes are the same for all. These include eye, kidney, and nerve problems. These problems are caused by many years of blood sugar levels that are too high. Every person’s goal for diabetes treatment, no matter what kind they have, is to keep blood sugar levels as normal as they can. This helps to prevent diabetes-caused problems.

Complications with Hyperglycemia:

          Vision Problems

          Kidney Problems

          Neurological Problems (Nerve Damage)

Goal: To Keep Blood Sugar Levels Normal

              A1C: 7%

              A1C may also be reported as eAG: 154 mg/dl

              Before a meal (preprandial plasma glucose): 70–130 mg/dl

              1-2 hours after beginning of the meal (Postprandial plasma glucose)*: Less than 180 mg/dl

ADA Normal Blood Sugar Levels

Managing Cystic Fibrosis-Related Diabetes




Cystic Fibrosis and Infertility in Males

Cystic fibrosis causes the buildup of thick, sticky mucus within vital organ systems in the human body. One of these systems affects the reproduction system in males with cystic fibrosis. Approximately 98% of CF men are infertile due to the inability of the vas deferens to properly function. The vas deferens is the tube which carries sperm from the testis to the penis. The epididymis sits on top of the testis like a cap. Normally, the vas deferens carries the newly made sperm to the back of the prostate gland where it joins the outlets of the seminal vesicles. The sperm can then be released into the semen during intercourse. In CF the vas deferens almost always fails to develop properly.

Thanks to reproductive technologies, sperm can be extracted from the epididymis (fine tubules behind the testis) by procedures such as microepididymal sperm aspiration (MESA), or testicular sperm extraction (TESE), or percutaneous epididymal sperm aspiration (PESA).

Sperm are collected during an operation, generally done under local anesthesia. Once collected; a single sperm is injected directly into the egg through intracytoplasmic sperm injection (ICSI). This procedure is done in combination with in vitro fertilization.

According to the Mayo Clinic though, almost all men with cystic fibrosis are infertile because the tube that connects the testes and prostate gland (vas deferens) is either blocked with mucus or missing entirely. Certain fertility treatments and surgical procedures sometimes make it possible for men with cystic fibrosis to become fathers.

Sexuality, Infertility, and Cystic Fibrosis: Information for Adults

CF males

CF and Macronutrients

Adequate calories to support normal growth and development are essential, especially in the presence of pancreatic insufficiency. Energy intake should be based on the patterns of weight gain and growth in the person. If an individual has significant growth deficits, lung disease, or malabsorption, energy requirements may be significantly increased. Currently there is no perfect method to estimate the caloric needs of a person with CF. Instead, a steady rate of weight gain in growing individuals should be the goal. For adults, the desired outcome is to maintain an acceptable weight in relation to height with optimal fat and muscle stores.

To obtain adequate calories and compensate for any fat malabsorption, individuals with CF often require a greater fat intake than what is normally recommended for the general population. Fat restriction is not recommended, because fat is an important energy source, and pancreatic enzyme replacement therapy is used to aid its absorption. Medium-chain triglycerides (MCT) require less lipase activity than long-chain fatty acids and may be utilized as a better source of fat calories. MCT have a fatty acid chain length between 6 and 12 carbons, making them short enough to be water soluble. They require less bile salt for solubilization and can be transported as free fatty acids through the portal system. Adequate protein intake is essential to meet the needs of growing individuals and maintain protein stores. Good nutrition also plays an important role in preparing the individual with cystic fibrosis for potential transplant later on in life.

Nutrition management is critical for the health and survival of patients with cystic fibrosis-related diseases. Since a majority of these patients have difficulty maintaining weight, calorie restriction is never appropriate. For patients on insulin, carbohydrate counting offers a great degree of flexibility. Patients should be able to eat as they choose with appropriate insulin coverage. Although carbohydrate is not restricted, patients should be taught to distribute carbohydrate calories throughout the day and to avoid concentrated carbohydrate loads.

CF diagram

Pancreatic Complications in Cystic Fibrosis

The pancreas, located behind the stomach in the center of the abdomen, extends into the left side of the abdomen. It is connected to the first part of the intestine, the duodenum. The pancreas secretes enzymes that aid food digestion and help to regulate blood sugar.

In CF, the altered transport of electrolytes across pancreatic tissues leads to abnormal production of digestive enzymes. Decreased production of sodium bicarbonate makes pancreatic secretions dehydrated and thickened, blocking the pancreatic ducts. Despite these blockages, the pancreas continues to make more enzymes required for food digestion. These abundant enzymes damage the pancreatic tissue, eventually leading to fibrosis of the pancreas until it is no longer able to produce enough enzymes to properly digest food.

Pancreatic insufficiency occurs when the pancreas loses about 90% of its ability to secrete digestive enzymes. Patients become unable to digest food properly, which leads to the malabsorption of nutrients, or even malnutrition. Vitamins, such as A, B12, D, E, and K, and fats, are the most important nutrients that are not absorbed when a patient has pancreatic insufficiency. 

The impaired absorption of fats causes diarrhea, weight loss, and malnutrition, but supplemental pancreatic enzymes can help with digestion of fats and reduce diarrhea. Approximately 80% of CF patients develop pancreatic insufficiency.

The following vitamin deficiencies result from pancreatic insufficiency:

Vitamin A: Visual and Skin Changes

Vitamin B12: Anemia

Vitamin D: BoneAbnormalities

Vitamin E: NeurologicalProblems

Vitamin K: BloodClottingProblems

CK vitamins


Pancreatic Enzyme Replacement Therapy in CF Patients

Cystic fibrosis is the most common fatal genetic disorder in North America. CF affects the epithelial transport in exocrine tissues. The disorder produces thick, sticky mucus secretions that may seriously impair the function of various organ systems. The organ systems that are affected include the respiratory tract, the gastrointestinal tract, the liver, the genitourinary system, and the sweat glands.

CF has three major consequences: chronic lung disease, pancreatic insufficiency, and abnormally high electrolyte concentrations in the sweat.

Cystic fibrosis causes pancreatic insufficiency in most cases, causing 85-90% of serious cases to require pancreatic enzyme replacement therapy (PERT). With age, damage to the pancreas becomes worse. The thick mucus obstructs the small pancreatic ducts and interferes with the secretion of digestive enzymes, pancreatic juices, and pancreatic hormones. Eventually, the pancreatic cells are surrounded by mucus and are gradually replaced by fibrous tissues. Malabsorption of many nutrients including fat, protein, vitamins, and minerals often leads to malnutrition. Additionally, the secretion of insulin may be affected resulting in glucose intolerance and diabetes.

With high energy needs, fat restrictions are inappropriate. Instead, pancreatic enzyme replacements are used to control Steatorrhea, relieve abdominal pain, and reduce the mass and frequency of stools passed. To improve the effectiveness of the enzyme replacements, H2-blockers are often provided as well. Even with enzyme replacements, from 10-20% of food energy is lost in the stools.

Pancreatic insufficiency has a strong influence on nutrition status and is a predictor of long-term outcome. The thickened secretions obstruct the pancreatic ducts and prevent the secretions of lipase, amylase, proteases, and bicarbonate. When pancreatic insufficiency is present, individuals are treated with pancreatic enzyme extracts. All enzyme products contain the various enzymes synthesized by the pancreas, including amylase, proteases and lipase in varying amounts. Commercial enzyme products vary in lipase activity from 4,000-25,000 U lipase/capsule. They are available in powder form as tablets that are acid labile or as enteric-coated microspheres- the enteric coating is designed to protect the enzyme from destruction by the acidic environment of the stomach.

Pancreatic enzymes are always taken when food or beverages are consumed. The dosage for enzymes in individualized based on the patient’s diet, nutritional status, degree of pancreatic insufficiency, intestinal pH, and GI anatomy and physiology. Because of inconsistencies in enzyme formulations, the Food and Drug Administration (FDA) has issued a rule requiring manufacturers of pancreatic enzyme supplements to obtain approval for their products. Prior to obtaining approval, manufacturers will need to test the enzymes in clinical trials and demonstrate that they are safe and effective. This rule means that the FDA now requires pancreatic enzymes to meet the same standards of testing as any other new drug.