Type 4 diabetes is a proposed classification of diabetes characterized by insulin resistance in older adults who are not overweight or obese. While not yet officially recognized as a distinct type of diabetes, researchers believe type 4 diabetes may account for a significant number of diabetes cases, especially in those over age 65.
Understanding the causes, symptoms, diagnosis, and management of type 4 diabetes is key to improving detection and outcomes. This blog post explores what is currently known about this emerging diabetes subtype.
- Type 4 diabetes is a proposed form of diabetes characterized by insulin resistance in older adults who are not overweight. It is not yet an official medical diagnosis.
- Researchers believe it may be caused by an accumulation of immune cells called regulatory T cells as part of the natural aging process.
- Symptoms are similar to other forms of diabetes but it may go undiagnosed in leaner older adults.
- There is no standardized treatment yet but medications for type 2 diabetes can help manage blood sugar levels.
- More research is needed to confirm causes in humans and develop customized treatments.
What Is Type 4 Diabetes?
You’ve probably heard of type 1 and type 2 diabetes. According to the Centers for Disease Control and Prevention (CDC)Trusted Source, more than 34 million Americans have diabetes — but the actual number might be much higher. A 2015 study with mistrusted Sources indicates that diabetes might be underdiagnosed in older adults who don’t have overweight or obesity. While not an official classification of diabetes, researchers are calling this type 4 diabetes.
Despite coining the term ‘type 4 diabetes’, it is currently not a recognised medical condition and hence there are no diagnostic criteria as yet; the proposed concept of ‘type 4 diabetes’ is in its infancy.
Type 4 diabetes isn’t an autoimmune condition like type 1 diabetes, and it’s not linked to weight like type 2 diabetes. Instead, this potential type of diabetes may be linked to the aging process. Research into this condition is ongoing, but scientists have already uncovered some connections.
Types of Diabetes
Diabetes is often thought of as having two distinct types, though gestational diabetes is also quite common. All types of diabetes cause high blood sugar because your body has trouble producing insulin, a hormone that moves and stores sugar.
Most Common Types
- Type 1 diabetes. Type 1 diabetes is most commonly diagnosed in children and teenagers. It’s an autoimmune condition. When you have type 1 diabetes, your immune system attacks the cells in your pancreas responsible for making insulin.
- Type 2 diabetes. Type 2 diabetes happens when your body stops responding to the insulin your pancreas makes. Over time, your pancreas also stops producing enough insulin. It’s generally linked to a combination of genetic and lifestyle factors.
- Gestational diabetes. This type of diabetes is a response to the hormonal changes that happen during pregnancy. The hormones made in the placenta can lower your body’s sensitivity to insulin. This may result in high blood sugar during pregnancy. Gestational diabetes is common in women who are already overweight when they become pregnant or who gain excessive weight during their pregnancies.
Other Specific Types
- MODY (maturity onset diabetes of the young). This type of diabetes occurs due to a genetic change, and runs in families. Children with the genetic change will often develop this form of diabetes by the time they are 25.
- Neonatal diabetes. Neonatal diabetes is generally diagnosed in children under 6 months old. It’s an inherited condition that’s different from type 1 diabetes because it’s not an autoimmune condition. Instead, children with this condition are born with a genetic change that affects their ability to produce insulin.
- Diabetes caused by other conditions. This type of diabetes is caused by conditions including cystic fibrosis, pancreatic cancer, or pancreatitis that damage the pancreas’ ability to produce insulin.
- Steroid-induced diabetes. This type of diabetes can happen when you take steroids that affect hormone production in your body.
Other Terms You May Hear
While these aren’t official types of diabetes, you may sometimes hear these terms when talking about diabetes. They include:
- Monogenic diabetes. This includes both MODY and neonatal diabetes, and refers to any type of diabetes that’s caused by genetic changes.
- Type 3c diabetes. This is sometimes used to refer to diabetes caused by other conditions, such as cystic fibrosis and pancreatic cancer.
- LADA (latent autoimmune diabetes in adults). This is sometimes referred to as type 1.5 diabetes. Some experts think of it as a subtype of type 1 diabetes. While it is an autoimmune disease like type 1 diabetes, LADA progresses more slowly. It’s often misdiagnosed as type 2 diabetes because you may still be able to produce insulin for some time.
Recent Discussion of New Types
Recently, some researchers have suggested that two additional types of diabetes might exist. These aren’t yet official diabetes types or diagnoses, but that might change as more information becomes available.
- Type 3 diabetes. Type 3 diabetes is used to explain the theory that insulin resistance might cause Alzheimer’s disease, a form of dementia. A 2018 research review showed that people with type 2 diabetes are more likely to develop Alzheimer’s disease. Experts are still investigating this link.
- Type 4 diabetes. Type 4 diabetes is the proposed term for diabetes caused by insulin resistance in older people who don’t have overweight or obesity. A 2015 study with miceTrusted Source suggested this type of diabetes might be widely underdiagnosed. This is because it occurs in people who aren’t overweight or obese, but are older in age.
Causes of Type 4 Diabetes
Scientists are just beginning to study type 4 diabetes, so they don’t yet have a lot of concrete information about what causes it.
A 2015 study with miceTrusted Source showed that the condition referred to as type 4 diabetes is linked to an excess of immune cells called regulatory T cells. Researchers have a theory that this is linked to the aging process, but studies in humans are still needed.
Symptoms of Type 4 Diabetes
Type 4 diabetes has many of the same symptoms as other types of diabetes. However, because it generally appears in people with a moderate weight, doctors may not suspect diabetes. Common symptoms include:
- Increased thirst
- Increased hunger
- Blurry vision
- Sores that don’t heal
- Frequent urination
- Unintentional weight loss
Many of these symptoms are also linked to other conditions and might not always indicate diabetes.
It’s a good idea to make an appointment with a medical professional if you’ve been experiencing any of these symptoms. A doctor can review your symptoms and order any tests they think are needed.
Diagnosing Type 4 Diabetes
There is no specific diagnostic test for type 4 diabetes yet since it is not an official diagnosis. However, doctors use the same screening and diagnostic tests for other types of diabetes to check for elevated blood sugar levels and insulin resistance.
Some common diabetes screening and diagnostic tests include:
- A1C test: This blood test provides an average of your blood sugar levels over the past 2-3 months. An A1C of 6.5% or higher indicates diabetes.
- Fasting blood sugar test: A blood sample is taken after fasting for at least 8 hours. A fasting blood sugar level of 126 mg/dL or higher indicates diabetes.
- Oral glucose tolerance test: Blood sugar levels are checked after fasting and then 2 hours after drinking a sugary drink. Higher than normal 2-hour blood sugar level indicates diabetes.
- Random blood sugar test: Blood sugar is checked at a random time without regard to meals. Levels of 200 mg/dL or higher, along with symptoms, suggest diabetes.
Your doctor will review your test results along with your risk factors, such as age and weight, to determine if you have diabetes and if type 4 diabetes is a possibility.
Treatment for Type 4 Diabetes
There is no specific treatment for type 4 diabetes yet. Researchers are working on developing medications to target the underlying immune cells dysfunction.
In the meantime, type 4 diabetes is treated similarly to type 2 diabetes using medications such as:
- Metformin: Helps reduce liver glucose production and improve insulin sensitivity.
- Sulfonylureas: Stimulate the pancreas to produce more insulin.
- DPP-4 inhibitors: Slow breakdown of incretins to keep insulin production steady.
- SGLT2 inhibitors: Prevent kidney reabsorption of glucose.
- GLP-1 receptor agonists: Slow digestion and reduce appetite to lower blood sugar.
Insulin may also be prescribed if needed to achieve blood sugar control.
Lifestyle modifications like weight loss and exercise are often less relevant for lean patients with type 4 diabetes. The focus should be on managing blood sugar levels through diet, medication, and regular testing.
Preventing Type 4 Diabetes
Research into whether type 4 diabetes can be prevented is still in very early stages. Some experts speculate that since aging appears connected to type 4 diabetes risk, steps to promote healthy aging could be beneficial. This may include:
- Eating a balanced, nutritious diet
- Engaging in regular physical activity
- Maintaining social connections
- Managing stress
- Getting quality sleep
- Keeping mentally active
However, more studies are needed to confirm if any interventions can reduce the risk of developing type 4 diabetes specifically. Routine screening for diabetes is recommended for all adults over age 45, regardless of weight.
Takeaway on Type 4 Diabetes
Insulin resistance is a hallmark of type 2 diabetes, and is often connected with having obesity. However, Type 4 diabetes shows that this isn’t always the case.
Studies in mice have shown that the aging process can cause the body to produce too many regulatory T cells. These cells can lead to type 4 diabetes.
These results still need to be studied in humans. Finding evidence of this same pattern in humans could lead to increased diagnosis and the development of new treatments for diabetes.
Frequently Asked Questions
What are the common symptoms of type 4 diabetes?
The symptoms of type 4 diabetes are similar to other forms of diabetes, including increased thirst, frequent urination, fatigue, blurred vision, slow healing wounds, and unexplained weight loss.
How is type 4 diabetes diagnosed?
There is no official diagnostic criteria yet but blood tests for insulin resistance along with patient risk factors like older age and lean weight can indicate type 4 diabetes.
Is type 4 diabetes preventable?
More research is needed, but healthy lifestyle habits may help lower risk as people age. However, some degree of insulin resistance may be an unavoidable aspect of aging.
How is type 4 diabetes treated?
There are no customized treatments yet, but medications used for type 2 diabetes can help control blood sugar levels. Lifestyle measures like weight loss are less relevant for lean patients.
Is type 4 diabetes a recognized medical diagnosis?
No, type 4 diabetes is still a proposed classification without official medical recognition. More research on causes, prevention, and treatment in humans is needed.