Secondary diabetes is diabetes caused by another condition or a medical treatment. Dozens of conditions can damage the body’s complex regulation of glucose and insulin levels. For example:
- Pancreatitis, cystic fibrosis or hemochromatosis can disrupt pancreas function.
- Endocrine disorders such as acromegaly or Cushing’s syndrome may alter the production of hormones.
- Certain drugs and chemicals promote insulin resistance or hyperglycemia.
- Genetic mutations can interfere with the body’s ability to produce and use the hormones that control glucose.
Unlike most forms of diabetes, secondary diabetes is sometimes temporary. However, some cases of secondary diabetes, such as those resulting from a total pancreatectomy, will be chronic.
Secondary diabetes is similar to other forms of diabetes in its signs and symptoms, as well as its diagnosis. However, the primary condition may mask indicators of secondary diabetes in some cases. Patients who experience possible symptoms of diabetes, such as unexplained weight loss and excessive urination and thirst, are advised to see their physician. The disease is diagnosed with glucose tests.
Treating secondary diabetes involves resolving its cause, if possible. If its cause cannot be resolved, the focus turns to controlling the diabetes. This may involve exercise, diet, insulin therapy and antidiabetic agents.
About secondary diabetes
Secondary diabetes is diabetes that occurs as a result of another disease or factor. Secondary diabetes is uncommon. The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) estimates that it accounts for 1 to 2 percent of all diabetes cases, and the National Diabetes Education Program puts that figure at 1 to 5 percent.
Diabetes is a disorder in the body’s ability to use a hormone called insulin to process glucose (blood sugar) for energy. Type 1 diabetes is an autoimmune disease that destroys the insulin-making cells of the pancreas. Type 2 is a metabolic disorder, generally involving genetic and behavioral factors, excess weight and insulin resistance. Gestational diabetes is also a metabolic condition but is temporary and related to hormonal changes associated with pregnancy.
Secondary diabetes is sometimes defined as covering all cases that cannot be classified as type 1, type 2 or gestational. However, conditions that are often considered separately from secondary diabetes include latent autoimmune diabetes of the young (LADA), maturity-onset diabetes of the young (MODY), autoimmune polyglandular syndrome and Wolfram syndrome.
Secondary diabetes can be related to a wide variety of disorders and other conditions. For example, pancreatitis can damage the insulin-producing beta cells. Secondary diabetes may also occur in conjunction with many other diseases, such as cystic fibrosis, as well as certain medications or other medical treatments.
Except for gestational diabetes, most cases of diabetes are chronic. However, some forms of secondary diabetes may be a temporary condition that goes away when the condition causing the diabetes is treated. For example, if certain medications are causing a patient’s diabetes, ceasing use of those medications could return glucose levels to normal. However, no medication should be stopped or started without first consulting a physician. Other cases of secondary diabetes, such as those resulting from total pancreatectomy, will last the rest of the patient’s life.
Sometimes it is difficult or impossible to distinguish secondary from primary diabetes, especially cases involving insulin resistance, which would typically be considered type 2 diabetes. For example:
- Some research has linked exposure to certain plastics to insulin resistance, but if this did lead to secondary diabetes in a person it would likely go undetected, and other factors would typically contribute to the insulin resistance.
- An asthma patient may be obese, have a family history of type 2 diabetes and have been using oral corticosteroids for years. The excess weight, family history and medication could all contribute to diabetes, which in this patient would likely be diagnosed as type 2.
- Conditions including fatty liver disease and alcohol abuse may contribute to diabetes, but these cases too are often considered to be type 2.
Treatment of most cases of secondary diabetes is similar to that for type 2 diabetes. However, cases involving destruction of the beta cells will be treated more like type 1 diabetes and require insulin administration several times a day.
Potential causes of secondary diabetes
Secondary diabetes is diabetes that results from (is secondary to) other diseases and conditions. Many primary conditions can contribute to secondary diabetes, including:
- Other endocrine disorders. Examples include hyperthyroidism, conditions involving overactive adrenal glands such as Cushing’s syndrome, and conditions involving excessive levels of growth hormones such as acromegaly.
- Pancreatic disorders. Conditions that disrupt pancreas function and may lead to secondary diabetes include pancreatitis, excessive absorption of iron (hemochromatosis), physical trauma to the pancreas and pancreatic damage due to malnutrition.
- Some liver diseases. These include fatty liver disease and hepatitis C.
- Celiac disease (gluten intolerance). This and other autoimmune diseases increase the risk of autoimmune diabetes.
- Some cancers. Carcinoid tumors in the lungs, stomach or intestines can cause secondary diabetes by producing a hormone (ACTH) that causes the adrenal glands to overproduce cortisol. Adrenal and pituitary tumors can have this same effect. Pancreatic cancer can impair pancreas function.
- Drugs, chemical agents and toxins. Substances in the body can disrupt the normal function of the endocrine system and hormones it produces, and cause secondary diabetes. These may include:
- Two classes of antihypertensives (drugs for elevated blood pressure): diuretics and beta blockers
- Immunosuppressives including corticosteroids (glucocorticoids)
- Hormone supplements including growth hormones, anabolic steroids, estrogens, birth control pills, injected contraceptives, and hormone therapy for prostate cancer (gonadotropin-releasing hormone agonists)
- Antipsychotics, lithium and some antidepressants
- Antiretrovirals (HIV drugs)
- Some anticonvulsants (seizure medications)
- Some chemotherapy drugs
- Illegal and legal recreational drugs such as opiates and alcohol
In addition, some studies have linked common consumer plastics and plastics ingredients including phthalates and bisphenol A to insulin resistance. Other chemicals including the defoliant Agent Orange, dioxin (its active ingredient) and certain pesticides have also been linked.
- Other medical treatments including:
- Pancreatectomy. Removal of the pancreas, for conditions such as pancreatic cancer, other severe pancreatic disease or a form of hyperinsulinemia in babies called persistent hyperinsulinemic hypoglycemia of infancy (PHHI). Total pancreatectomy causes diabetes, and a partial pancreatectomy may, depending on how many of the beta cells are removed.
- Orchiectomy. Surgical removal of the testicles. Orchiectomy may be necessary to treat testicular cancer. It can also be, like hormonal drug therapy, a form of androgen deprivation therapy for prostate cancer. Recent studies indicate that androgen deprivation therapy and low levels of testosterone (male hypogonadism) may increase men’s risk of diabetes.
- Radiation therapy. This cancer treatment can cause hyperglycemia and increase the risk of diabetes.
There are many ways that secondary diabetes can develop. Examples include:
- Damage to or destruction of beta cells. Beta cells are the parts of the pancreas that produce and secrete insulin. The body’s cells cannot use glucose without insulin. The beta cells can be removed in a pancreatectomy, or destroyed or inhibited by diseases, chemicals or radiation. Beta cells may also function improperly due to genetic defects.
- Damage to the islets of Langerhans. The endocrine portions of the pancreas, which include alpha cells, beta cells and delta cells. They may be damaged by limited blood flow due to inflammation of the pancreas.
- Production of abnormal insulin or insulin receptors. Some genetic defects cause the beta cells to produce insulin molecules that are not recognized by body’s cells, preventing glucose transportation. Mutations can also cause cells to not recognize typical insulin.
Signs and symptoms of secondary diabetes
The signs and symptoms of secondary diabetes can often go unnoticed or undetected, especially in the presence of another condition or when taking certain medications. The symptoms are generally the same as those for type 1 diabetes or type 2 diabetes.
Possible signs and symptoms of secondary diabetes include:
- Excessive urination (polyuria)
- Excessive thirst (polydipsia)
- Extreme hunger (polyphagia)
- Unexplained weight loss
- Increased fatigue
- Sores that are slow to heal
- Numbness or tingling in the hands or feet
- Blurred eyesight or other vision changes
- Frequent infections, including gingivitis, thrush, yeast infections and urinary tract infections
Diagnosis methods for secondary diabetes
The diagnosis of secondary diabetes is similar to that of other forms of diabetes. Patients with conditions known to cause diabetes may undergo occasional glucose tests to screen for the disease before symptoms and complications start. These blood tests may include:
- Random plasma glucose test
- Fasting blood glucose test
- Oral glucose tolerance test
After confirmation of diabetes, the physician may review the patient’s medical history to look for possible causes, such as medications or inherited conditions. To try to identify the cause, the physician may order additional tests, such as:
- Blood tests for pancreatic enzymes to diagnose pancreatitis
- Genetic tests for mutations to the genes involved in insulin production
- Thyroid blood tests to identify hyperthyroidism
- C peptide test to assess levels of insulin in the blood
Patients may also have a blood pressure reading and cholesterol test because many people with diabetes have high blood pressure and unhealthy levels of cholesterol and other blood fats.
Treatment and prevention for secondary diabetes
Treating secondary diabetes involves treating its cause, if possible. In some cases, once the source is addressed, the diabetes will go away. This may be the case for diabetes caused by certain drugs. Discontinuing their use may stop the diabetes, although patients should consult their physician before beginning or stopping use of any medications. In some cases the benefits of medications, such as antiretrovirals for HIV/AIDS, outweigh the side effects.
When the underlying cause cannot be resolved or remains unidentified, the diabetes itself will need to be treated. Treating diabetes is complex and requires commitment from the patient. Initially, treatment focuses on controlling the level of glucose (blood sugar). This is accomplished with a combination of diet and exercise, and it may involve insulin therapy and antidiabetic agents.
Many forms of secondary diabetes are treated like type 2 diabetes. However, cases involving destruction of the insulin-making beta cells of the pancreas, such as those caused by pancreatectomy, can be treated like type 1 diabetes.
To monitor their diabetes during treatment, patients may use a glucose meter as instructed by their physician. Glucose monitoring can alert patients when their glucose levels are above or below their target range so they can identify and treat hyperglycemia and hypoglycemia according to their treatment plan. If readings are frequently out of range, the physician may recommend a change in the treatment of a patient’s diabetes or underlying condition.
Other important aspect of treating and monitoring diabetes include:
- Daily foot care and skin care
- Regular dental care
- Not smoking or abusing alcohol
- Ketone tests to help avoid diabetic ketoacidosis
- A sick-day plan devised by a physician
- Regular physical exams, eye exams and foot exams
- Microalbuminuria testing to monitor kidney function
- Blood pressure readings and cholesterol tests
- Seeing specialists in the care team as needed
Controlling diabetes can help prevent the many potential complications of the disease, such as heart conditions, stroke, diabetic retinopathy, diabetic nephropathy, diabetic neuropathy and sexual dysfunction.
Prevention of secondary diabetes depends on its cause. For instance, treating pancreatitis may help preserve the pancreas’ ability to produce insulin and prevent diabetes. As another example, quitting the abuse of narcotics or alcohol may help prevent damage to the beta cells that can lead to diabetes.
Questions for your doctor on secondary diabetes
Preparing questions in advance can help patients have more meaningful discussions with healthcare providers regarding their condition. Patients may wish to ask their doctor the following questions about secondary diabetes:
- How does secondary diabetes differ from type 1 or type 2 diabetes?
- Could secondary diabetes be causing my symptoms? What else could be causing my symptoms?
- What diagnostic tests for diabetes might I need to undergo? What are my test results?
- What caused my secondary diabetes?
- If a medical treatment caused my diabetes, do I have other options, or do the benefits of this treatment outweigh the side effects?
- Is my diabetes permanent, or could it be temporary?
- Can the symptoms of my primary condition mask the symptoms of diabetes?
- How does treatment of my primary condition affect my secondary diabetes? Will treating my diabetes affect my other condition?
- Will changing my treatments help treat my secondary diabetes?
- What lifestyle changes do I need to make as treatment for my diabetes?
- Can conditions that I now have, or am at risk of developing, cause secondary diabetes? If so, how can I prevent it?
- What possible complications may occur due to the combination of my primary condition and secondary diabetes?