Type 2 Diabetes Overview
Type 2 diabetes is a disorder in the way the body regulates and uses sugar (glucose) as fuel. This long-term (chronic) condition causes too much sugar circulating in the bloodstream. Eventually, high blood sugar levels can lead to disturbances in the circulatory, nervous and immune systems.
In type 2 diabetes, there are primarily two interrelated problems. Your pancreas doesn't produce enough insulin, a hormone that regulates the movement of sugar into your cells, and cells respond poorly to insulin and take in less sugar.
Type 2 diabetes was formerly known as adult-onset diabetes, but both type 1 and type 2 diabetes can begin in childhood and adulthood. Type 2 is more common in older adults, but the increase in the number of children with obesity has led to more cases of type 2 diabetes in younger people.
There is no cure for type 2 diabetes, but losing weight, eating well, and exercising can help you manage the disease. If diet and exercise are not enough to manage your blood sugar, you may also need diabetes medication or insulin therapy.
The signs and symptoms of type 2 diabetes usually develop slowly. In fact, you may have been living with type 2 diabetes for years and you may not know it. When signs and symptoms are present, they may include:
- Increased thirst
- Frequent urination
- Increased feeling of hunger
- Unwanted weight loss
- Blurred vision
- Slow healing wounds
- Frequent infections
- Numbness or tingling in the hands or feet
- Dark areas of skin, usually in the armpits and neck
When to See a Doctor
See your doctor if you notice any signs or symptoms of type 2 diabetes.
Type 2 diabetes is primarily the result of two interrelated problems:
- Cells in muscle, fat, and liver become resistant to insulin. Because these cells don't interact normally with insulin, they don't get enough sugar.
- The pancreas cannot produce enough insulin to manage blood sugar levels.
It is not known exactly why this happens, but being overweight and sedentary are important contributing factors.
How Does Insulin Work?
Insulin is a hormone that comes from the gland behind and under the stomach (pancreas). Insulin regulates how the body uses sugar in the following ways:
- Sugar in the bloodstream triggers the pancreas to release insulin.
- Insulin circulates in the bloodstream and allows sugar to enter your cells.
- The amount of sugar in your bloodstream drops.
- In response to this drop, the pancreas releases less insulin.
The Role of Glucose
Glucose, a sugar, is the main source of energy for cells that make up muscles and other tissues. The use and regulation of glucose includes:
- Glucose comes from two main sources: food and your liver.
- Glucose is absorbed into the bloodstream where it enters cells with the help of insulin.
- Your liver stores and produces glucose.
- When your glucose levels are low, such as when you haven't eaten for a while, the liver converts stored glycogen into glucose to keep your glucose levels within a normal range.
This process does not work well in type 2 diabetes. Instead of being transported to your cells, sugar accumulates in your bloodstream. As blood sugar levels increase, insulin-producing beta cells in the pancreas secrete more insulin. Eventually these cells break down and cannot produce enough insulin to meet the body's demands.
In the less common type 1 diabetes, the immune system mistakenly destroys beta cells and releases little or no insulin into the body.
Factors that can increase your risk of type 2 diabetes include:
- Weight. Being overweight or obese is the main risk.
- Fat distribution. Storing fat mostly in your abdomen rather than your hips and thighs indicates a greater risk. Your risk of type 2 diabetes increases if you are a man whose waist circumference is over 40 inches (101.6 centimeters) or if you are a woman measuring over 35 inches (88.9 centimeters).
- Inactivity. The less active you are, the greater your risk. Physical activity helps control your weight, uses glucose as energy, and makes your cells more sensitive to insulin.
- Family history. If your parent or sibling has type 2 diabetes, the risk of type 2 diabetes increases.
- Race and ethnicity. Although the cause is unclear, people of certain races and ethnicities, including Blacks, Hispanics, Native American and Asians, and Pacific Islanders, develop more type 2 diabetes than whites.
- Blood lipid levels. Increased risk is associated with low levels of high density lipoprotein (HDL) cholesterol - the "good" cholesterol - and high levels of triglycerides.
- Age. The risk of type 2 diabetes increases as you age, especially after the age of 45.
- Prediabetes. Prediabetes is a condition in which your blood sugar level is higher than normal but not high enough to be classified as diabetes. If left untreated, prediabetes usually progresses to type 2 diabetes.
- Risks associated with pregnancy. If you developed gestational diabetes while you were pregnant or gave birth to a baby weighing more than 9 pounds (4 kilograms), your risk of developing type 2 diabetes increases.
- Polycystic ovary syndrome. Having polycystic ovary syndrome, a common condition characterized by irregular menstrual periods, excessive hair growth, and obesity, increases the risk of diabetes.
- Dark areas of skin, usually on the armpits and neck. This condition usually indicates insulin resistance.
Type 2 diabetes affects many major organs, including your heart, blood vessels, nerves, eyes, and kidneys. In addition, factors that increase the risk of diabetes are risk factors for other serious chronic diseases. Managing diabetes and controlling your blood sugar can reduce your risk of these complications or coexistence (comorbidities).
Possible complications of diabetes and common comorbidities include:
- Heart and blood vessel disease. It is associated with an increased risk of diabetes, heart disease, stroke, high blood pressure, and narrowing of blood vessels (atherosclerosis).
- Nerve damage (neuropathy) in the limbs. Over time, high blood sugar can damage or destroy nerves, causing tingling, numbness, burning, pain, or eventually loss of sensation, which usually begins at the fingertips and gradually spreads upward.
- Other nerve damage. Damage to the heart nerves can contribute to irregular heart rhythms. Nerve damage in the digestive system can cause problems with nausea, vomiting, diarrhea, or constipation. Nerve damage in men can cause erectile dysfunction.
- Kidney disease. Diabetes can lead to chronic kidney disease or irreversible end-stage kidney disease that may require dialysis or kidney transplant.
- Eye damage. It increases the risk of serious eye diseases such as diabetes, cataracts and glaucoma, and can damage the blood vessels of the retina, potentially leading to blindness.
- Skin condition. Diabetes can make you more susceptible to skin problems, including bacterial and fungal infections.
- Slow recovery. Left untreated, cuts and blisters can develop into serious infections that can heal badly. Serious damage may require amputation of fingers, feet or legs.
- Hearing impairment. Hearing problems are more common in people with diabetes.
- Sleep apnea. Obstructive sleep apnea is common in people living with type 2 diabetes. Obesity may be the main contributing factor for both conditions. It is not clear whether treating sleep apnea improves blood sugar control.
- Dementia. It seems to increase the risk of type 2 diabetes, Alzheimer's disease, and other disorders that cause dementia. Poor control of blood sugar levels is linked to a faster decline in memory and other thinking skills.
Healthy lifestyle choices can help prevent type 2 diabetes, and this is true even if you have biological relatives living with diabetes. If you've been diagnosed with prediabetes, lifestyle changes can slow or stop the progression to diabetes.
A healthy lifestyle includes:
- Eating healthy foods. Choose foods that are lower in fat and calories and high in fiber. Focus on fruits, vegetables and whole grains.
- Being active. Aim for 150 minutes or more of moderate to vigorous aerobic activity per week, such as brisk walking, cycling, jogging, or swimming.
- Lose weight. Losing a modest amount of weight and keeping it off can delay the progression from prediabetes to type 2 diabetes. Your prediabetes