By Carolien Koreneff, CDE-RN

There is a lot of information available about the different types of diabetes and risk factors, but some people do not fit into those categories. You may see clients that develop diabetes as a result of medications they have to take for other health conditions, or after surgery. There are also people who develop diabetes due to damage to their pancreas from cancer or infections such as pancreatitis.

While diabetes is typically managed in a similar way regardless of its cause, understanding the different ways it can develop can be valuable in providing informed care.

Medications that can cause diabetes

Taking certain medications for other health conditions can increase the risk of developing diabetes.

Antipsychotics

Atypical Antipsychotic Agents (AAAs) are commonly used to treat mental health conditions such as schizophrenia and psychosis.

These medications can increase hunger and the associated increased food consumption can lead to weight gain. Overweight and obesity can lead to high blood glucose levels due to insulin resistance.

Some antipsychotic medications can also affect insulin production and less insulin secretion increased glucose levels. However, even before antipsychotic drugs appeared, there was evidence that diabetes was more common in patients with schizophrenia and some other mental health conditions.

Beta blockers

Certain heart conditions, high blood pressure and even glaucoma are often treated with a beta blocker.

Beta blockers have been linked to the development of diabetes, as they tend to reduce insulin sensitivity. They can also hide the signs of hypoglycaemia (low blood glucose levels), and can prolong the effect of any hypos. However, there are different types of beta blockers and not all of them affect glucose levels.

Beta blockers are very important in treating certain heart conditions and are not associated with an increased risk of the development of hypos. If your client has concerns, refer them to their doctor.

Corticosteroids

Steroids can raise blood glucose levels as they block the action of insulin, causing insulin resistance. Steroid injections can cause glucose levels to rise soon after administration and the effect may last three to 10 days. The effect of oral steroids depends on the time, the dose and the type of steroid and may raise glucose levels a few days after starting the treatment. Inhaled steroids, such as those used in puffers to treat asthma, do not affect blood glucose levels.

Long-term use of steroids is associated with a high risk of developing diabetes.

Diuretics

Thiazide diuretics can be prescribed to reduce high blood pressure by removing excess fluid from the body. They can also be taken to reduce heart problems and should never be stopped without approval from an individual’s doctor.

Some older studies showed that thiazide diuretics increased the risk of diabetes, but this risk is reduced in lower doses. Newer data has found glucose rises to be very small and clinically unimportant.

As thiazides can significantly reduce the risk of heart failure the benefits are said to outweigh the risk of any worsening glucose levels.

Statins

Although some studies suggest that statins may increase the risk of developing diabetes, this is usually only if an individual is taking high doses of statins. People already diagnosed with diabetes are at higher risk of cardiovascular complications and statins can help decrease this risk. If your client raises concerns about the pros and cons of taking this type of medication, refer them to their doctor.

Secondary diabetes

Some people develop diabetes due to damage to the pancreas by other causes. These can include surgery, cancer and infections such as pancreatitis. The treatment of this type of diabetes depends on the cause and the extend of the damage.

Type 3c diabetes

According to the American Diabetes Association (ADA) and the World Health Organization (WHO), Type 3 diabetes covers a wide range of specific types of diabetes. This includes various defects of beta cell function, genetic defects in insulin action and diseases of the pancreas. Currently people with type 3 diabetes (as defined by the ADA and WHO) are grouped as “other diabetes” for NDSS purposes.

It can get confusing as some people refer to the term type 3 diabetes to describe diabetes that is linked to Alzheimer’s disease. Some scientists proposed the term type 3 because they believe insulin dysregulation in the brain causes dementia. It is important to note that type 3 diabetes is not an officially recognised health condition.

Type 3c diabetes can develop when the pancreas gets damaged in such a way that it is unable to produce insulin. This could be due to conditions such as cystic fibrosis, haemochromatosis, chronic pancreatitis, a pancreatectomy or pancreas cancer.

Cystic fibrosis

Cystic fibrosis is a chronic, genetic, multisystem disorder that causes thick, sticky mucus to build up in organs such as the lungs and pancreas. This can scar the pancreas and prevent the production of enough insulin. Although the pancreas still makes insulin, it is not enough to keep blood glucose levels within a normal range. People with cystic fibroses can also develop insulin resistance linked to steroid treatment and are at higher risk of developing gestational diabetes in pregnancy, requiring insulin treatment.

Haemochromatosis

Haemochromatosis is a condition where too much iron is absorbed in the body. The extra iron is stored in the liver and pancreas and affects insulin production. This can increase the risk of developing diabetes. The excess iron in the body can cause the skin to darken and hence diabetes related to haemochromatosis is sometimes also called bronze diabetes.

Pancreatitis

Pancreatitis can affect the amount of insulin the body produces. It can be acute or chronic and can develop due to a range of causes. Chronic pancreatitis can lead to fibrosis and lead to the pancreas no longer being able to make enzymes and hormones such as insulin.

Chronic pancreatitis can occur due to genetics but more commonly pancreatitis is acquired through blockages in the bile duct caused by gallstones or due to excessive alcohol use.

Chronic pancreatitis is the most common cause of type 3c diabetes.

Pancreatic cancer

Pancreatic cancer can cause cells to become resistant to insulin, resulting in an increase in blood glucose levels. Pancreatic cancer can also stop the beta cells of the pancreas making more insulin to deal with any insulin resistance. This similarly results in the development of diabetes. In fact, about 50% of people diagnosed with pancreatic cancer also have diabetes.

Surgery that can cause diabetes

Surgery and the effects of anaesthesia put stress on the body that may result in elevated blood glucose levels. Around the time of surgery there are often also changes in lifestyle that may affect blood glucose levels.

The most common cause for higher glucose levels after surgery is linked to an increase in the stress hormone cortisol and due to an increase in catecholamines. Both cortisol and catecholamines can increase insulin resistance.

Even just slightly elevated blood glucose levels can cause a delay in healing and increase the risk of infections.

Pancreatectomy

There are many reasons why a person may need a pancreatectomy, including cysts in the pancreas, pancreatic cancer and severe chronic pancreatitis. This type of surgery often leads to the development of type 3c diabetes.

A partial pancreatectomy will leave some beta cells behind and sometimes this is enough to keep glucose levels in the target range. A total pancreatectomy on the other hand will generally lead to diabetes. Many people will end up needing insulin injections.

Whipple’s procedure

The Whipple procedure, also called a pancreaticoduodenectomy, is often used to treat tumours and other conditions in the pancreas, small intestine and bile ducts. It involves removing the head of the pancreas, the first part of the small intestine, the gallbladder and the bile duct.

Depending on how much of the pancreas the surgeon has to remove, type 3c diabetes can occur after this type of surgery.

Diagnosing type 3c

It is difficult for health providers to diagnose type 3c, so it is not uncommon for people to be misdiagnosed as having type 2 diabetes instead.

To diagnose type 3c a doctor will have to confirm damage to the pancreas and rule out other types of diabetes. They can do this through pancreas specific blood tests, CT scans or an MRI scan.

Managing type 3c diabetes

Treatment is generally the same as those with type 2 diabetes, if residual pancreas function is left.  If the whole pancreas has to be removed, or is no longer working, insulin treatment similar to type 1 diabetes is often needed.

Clients that have had a total pancreatectomy, may also need enzyme replacement therapy to help them digest their food. Many people with pancreatic cancer also need to take pancreatic enzyme replacement therapy (PERT).

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