Diabetes

Types of diabetes

The most common types of diabetes are Type 1, Type 2 and gestational diabetes (which occurs during pregnancy). Rare types affect about 2% of people with diabetes. These less common types can be related to other health conditions, such as cystic fibrosis or pancreatitis, steroid use or genetic disorders.

Monogenic diabetes, which is also rare, is an umbrella term used to describe diabetes caused by changes in one of 20 genes that regulate blood sugar. It includes maturity-onset diabetes of the young, which usually develops before age 25, and neonatal diabetes mellitus, which develops when a baby is 6 to 12 months old.

Types 1, 2 and gestational diabetes affect most people with the condition, and here is how they differ:

• Type 1 diabetes: This is an autoimmune condition in which the immune system attacks insulin-producing cells in the pancreas. As a result, the body doesn’t produce enough.
• Type 2 diabetes: Type 2 diabetes is when your body is not able to make or use insulin effectively. It is typically diagnosed in adults but also occurs in children.
• Gestational diabetes: This type usually occurs in the second or third trimester of pregnancy and typically goes away after birth. The exact cause is unknown.

Diabetes comes in several forms—Type 1, Type 2, gestational diabetes and some rare types. Each has different causes and treatment approaches, but all require ongoing care and management to prevent complications.

What causes diabetes?

Diabetes is caused by having too much glucose (or sugar) in your blood.

When you eat carbohydrates, your body breaks them down into glucose. Your pancreas detects an increase in glucose and produces insulin, which helps the glucose get into your blood cells, where it can be used as energy. If you have diabetes, this system does not work properly.

With Type 1 diabetes, your immune system attacks the cells that make insulin, so your pancreas may not produce any insulin at all, or it may produce very little insulin. Doctors don’t know what causes the immune system to attack healthy cells, but research shows that genetics and environmental factors play a role.

With Type 2 diabetes, your pancreas can’t produce enough insulin, and your cells struggle to use the insulin it does produce (this is a condition called insulin resistance). As a result, your blood glucose level remains high, and your cells do not have the energy they need. Doctors don’t fully understand why Type 2 diabetes occurs, but lifestyle factors, such as being overweight or physically inactive, seem to play a role.

Diabetes risk factors

Anyone can develop diabetes, but you might be at higher risk if you have certain risk factors, such as:

• Age: Your risk of Type 2 diabetes increases as you get older. Type 1 diabetes is more common in children and young people.
• Ethnicity: Black people and those from American Indian, Asian American, Hispanic or Pacific Islander backgrounds are more likely than other groups to be diagnosed diabetes.
• Family history: Having a close relative with diabetes increases your risk.
• Having a large baby: Giving birth to a baby weighing 9 pounds or more increases your risk of Type 2 diabetes and gestational diabetes.
• High blood pressure: High blood pressure is strongly linked to an increased risk for Type 2 diabetes, but the exact connection is unknown.
• History of gestational diabetes: Although gestational diabetes goes away after you have your baby, it increases your risk of Type 2 diabetes later in life.
• Other health conditions: Some health conditions, such as polycystic ovary syndrome (PCOS), are linked to insulin resistance, which increases your diabetes risk.
• Prediabetes: If you have been diagnosed with prediabetes, you are more likely to develop Type 2 diabetes.
• Sedentary lifestyle: Sitting for long periods of time or not exercising regularly contributes to weight gain, which can put you at greater risk for developing diabetes.
• Smoking: Studies suggest that smokers are between 30% and 40% more likely to develop Type 2 diabetes.
• Weight: You are more likely to develop diabetes if you have a body mass index of 25 or higher or have a large waist size.

Complications of diabetes

Diabetes can cause serious and life-threatening complications. High blood sugar levels can damage blood vessels and nerves over time, reducing blood flow to other parts of your body and damaging organs and tissues. This is why it’s so important to manage the condition and prioritize your well-being if you live with diabetes.

Complications of diabetes include:

• Brain health: Diabetes can affect neurons in your brain, preventing them from responding to insulin. Diabetes can increase the risk of memory problems and dementia.
• Dental problems, including gum disease: High blood sugar and reduced saliva production can affect your teeth and gums.
• Diabetic ketoacidosis: This serious condition can develop suddenly and is caused by a lack of insulin or certain diabetes medications, like SGLT2 inhibitors. DKA causes a buildup of acids called ketones and requires immediate medical care.
• Eye conditions: Diabetes can damage your eyes over time, leading to poor vision, diabetic retinopathy or blindness.
• Foot problems: Blood vessels supplying the nerves in your feet can be damaged, leading to pain, diabetic ulcers and infections. If not treated early, these issues can become serious and may even lead to amputation.
• Kidney disease: Diabetes is a leading cause of kidney disease, due to high blood pressure and blood vessel damage in the kidneys.
• Nerve damage: Also known as diabetic neuropathy, can affect many parts of your body, causing symptoms like numbness, tingling or pain—especially in your hands and feet—and may also impact your internal organs.
• Metabolic dysfunction-associated steatotic liver disease (MASLD): This is a common condition where fat builds up in the liver. It usually doesn’t cause symptoms at first, but over time can lead to serious liver problems if not managed.
• Sexual and bladder problems: Diabetes can cause damage to nerves in your genitals and urinary tract.
• Skin conditions: Diabetes can affect your skin, causing problems like itching, irritation, infections, blisters, bumps, and rashes. These issues may be due to changes in blood flow, your medications or high blood glucose levels.

Frequently asked questions