Type 2 Diabetes

Type 2 diabetes occurs when the body cannot use insulin properly and sugar builds up in the blood. It was previously known as adult-onset diabetes.

Over time, high blood sugar levels in type 2 diabetes can damage the eyes, kidneys, nerves, and heart. This can happen because the pancreas does not produce enough insulin, a hormone that helps sugar enter the cells. It also occurs because the cells respond poorly to insulin, absorbing less sugar.


Both type 1 and type 2 diabetes can begin in childhood or adulthood. Type 2 diabetes is more common in older adults. However, the increase in the number of children with obesity has led to a rise in the incidence of type 2 diabetes among young people.

There is no cure for type 2 diabetes. Losing weight, eating a healthy diet, and exercising can help manage the disease. If diet and exercise are not enough to control blood sugar levels, diabetes medications or insulin therapy may help.


Symptoms

Symptoms of type 2 diabetes often develop slowly. In fact, people can live with type 2 diabetes for years without knowing it. When symptoms do appear, they may include:

  • Increased thirst.
  • Frequent urination.
  • Increased hunger.
  • Weight loss.
  • Fatigue.
  • Blurred vision.
  • Slow-healing sores.
  • Frequent infections.
  • Numbness or tingling in the hands or feet.
  • Areas of darkened skin, most often in the armpits and neck.

When to see a doctor

See your healthcare provider if you have any symptoms of type 2 diabetes.

Causes

Type 2 diabetes is mainly the result of two problems:

  • Muscle, fat, and liver cells do not respond to insulin as they should. As a result, they do not absorb enough sugar.
  • The gland that produces insulin, called the pancreas, cannot produce enough to keep blood sugar levels within a healthy range.

Being overweight and lack of physical activity are key factors.

How insulin works

Insulin is a hormone that comes from a gland located behind and below the stomach. This gland is called the pancreas. Insulin regulates how the body uses sugar in the following ways:

  • The presence of sugar in the bloodstream causes the pancreas to release insulin.
  • Insulin in the bloodstream moves sugar into the cells.
  • The amount of sugar in the bloodstream decreases.
  • The pancreas then releases less insulin.

The role of glucose

A sugar called glucose is a main source of energy for the cells that make up muscles and other tissues.

  • Glucose comes from two main sources: food and the liver.
  • Glucose passes into the bloodstream. There, with the help of insulin, it enters the cells.
  • The liver stores glucose in the form of glycogen and also produces it.
  • When glucose levels are low, the liver breaks down stored glycogen into glucose. This keeps the body's glucose level within a healthy range.

In type 2 diabetes, this process does not work properly. Instead of entering the cells, sugar builds up in the blood. As blood sugar levels rise, the pancreas releases more insulin. Over time, the insulin-producing cells in the pancreas become damaged. Then the cells cannot produce enough insulin to meet the body's needs.

Risk Factors

Factors that may increase the risk of type 2 diabetes include:

  • Excess weight. Being overweight or obese is a major risk.
  • Increased waist size. Storing fat mainly in the abdomen, rather than in the hips and thighs, increases the risk. The risk of type 2 diabetes is higher in people assigned male at birth whose waist measures more than 40 inches (101.6 cm). For people assigned female at birth, a waist circumference greater than 35 inches (88.9 cm) also increases the risk.
  • Inactivity. The less active a person is, the greater the risk. Physical activity helps control weight, uses glucose as an energy source, and helps cells absorb insulin.
  • Family history. Having a parent or sibling with type 2 diabetes increases the risk.
  • Race and ethnicity. It is not clear why, but people of certain races and ethnicities are more likely to develop type 2 diabetes than white people. These include Black, Hispanic, Native American, Asian, and Pacific Islander people.
  • Blood lipid levels. A higher risk is associated with low levels of high-density lipoprotein (HDL), also known as "good" cholesterol. A higher risk is also linked to elevated levels of a specific type of fat in the blood called triglycerides.
  • Age. The risk of type 2 diabetes increases with age, mainly after age 35.
  • Prediabetes. Prediabetes is a condition in which blood sugar levels are higher than normal but not high enough to be considered type 2 diabetes. If left untreated, prediabetes often progresses to type 2 diabetes.
  • Pregnancy-related risks. The risk of developing type 2 diabetes is higher in people who had gestational diabetes during pregnancy. It is also higher in those who gave birth to a baby weighing more than 9 pounds (4 kg).
  • Polycystic ovary syndrome. This condition causes irregular periods, excessive hair growth, and obesity. It also increases the risk of diabetes.

Complications

Type 2 diabetes affects many vital organs, including the heart, blood vessels, nerves, eyes, and kidneys. In addition, the factors that increase the risk of diabetes are also risk factors for other serious diseases. Managing diabetes and blood sugar levels can reduce the risk of these complications and other medical conditions, including:

  • Heart and blood vessel disease. Diabetes is linked to a higher risk of heart disease, stroke, high blood pressure, and narrowing of the blood vessels, known as atherosclerosis.
  • Nerve damage in the arms and legs. This condition is called neuropathy. High blood sugar levels over time can damage or destroy nerves. Neuropathy can cause tingling, numbness, burning, pain, or loss of sensation. It usually begins at the tips of the toes or fingers and spreads slowly upward.
  • Other nerve damage. Damage to the nerves of the heart can cause arrhythmias. Damage to the nerves of the digestive system can cause nausea, vomiting, diarrhea, or constipation. Nerve damage can also cause erectile dysfunction.
  • Kidney disease. Diabetes can cause chronic kidney disease or irreversible end-stage kidney disease. End-stage kidney disease may require treatment with dialysis (mechanical kidney filtration) or a kidney transplant.
  • Eye damage. Diabetes increases the risk of serious eye conditions, such as cataracts and glaucoma. Diabetes can also damage the blood vessels of the retina, the part of the eye that detects light. This is known as diabetic retinopathy and can lead to blindness.
  • Skin conditions. Diabetes can increase the risk of certain skin problems, including bacterial and fungal infections.
  • Slow healing. Cuts and blisters that are not treated can become serious infections. These infections may heal poorly. Severe damage may require surgery to remove a toe, foot, or leg. This surgery is called amputation.
  • Hearing impairment. Hearing problems are more common in people with diabetes.
  • Sleep apnea. Obstructive sleep apnea is common in people with type 2 diabetes. Obesity may be the main cause of both conditions.
  • Dementia. Type 2 diabetes appears to increase the risk of Alzheimer's disease and other conditions that cause dementia. Poor blood sugar control is linked to faster loss of memory and other cognitive abilities.

Prevention

Healthy lifestyle habits can help prevent type 2 diabetes. If you have prediabetes, lifestyle changes can slow its progression or prevent it from becoming diabetes.

A healthy lifestyle includes the following:

  • Eat healthy foods. Choose foods that are low in fat and calories and high in fiber. Focus on fruits, vegetables, and whole grains.
  • Stay active. Aim for 150 minutes or more per week of moderate to vigorous aerobic activity, such as brisk walking, cycling, running, or swimming.
  • Lose weight. If you are overweight, losing some weight and keeping it off can slow the progression from prediabetes to type 2 diabetes. If you have prediabetes, losing 7% to 10% of your body weight can reduce the risk of developing diabetes.
  • Don't sit for long periods. Sitting for extended periods can increase the risk of type 2 diabetes. Get up every 30 minutes and move around for at least a few minutes.

People with prediabetes may take metformin (Fortamet, Glumetza, and others), a diabetes medication, to reduce the risk of developing type 2 diabetes. This medication is usually prescribed to older adults with obesity who cannot control their blood sugar levels through lifestyle changes alone.