Type 1 diabetes signs and symptoms can come on quickly and may include:
- Increased thirst
- Frequent urination
- Bedwetting in children who previously didn't wet the bed during the night
- Extreme hunger
- Unintended weight loss
- Irritability and other mood changes
- Fatigue and weakness
- Blurred vision
- In females, a vaginal yeast infection
When to see a doctor
Consult your doctor if you notice any of the above signs and symptoms in you or your child.
The exact cause of type 1 diabetes is unknown. In most people with type 1 diabetes, the body's own immune system — which normally fights harmful bacteria and viruses — mistakenly destroys the insulin-producing (islet) cells in the pancreas. Genetics may play a role in this process, and exposure to certain environmental factors, such as viruses, may trigger the disease.
The role of insulin
Once a significant number of islet cells are destroyed, you'll produce little or no insulin. Insulin is a hormone that comes from the pancreas, a gland situated behind and below the stomach.
- The pancreas secretes insulin into the bloodstream.
- Insulin circulates, enabling sugar to enter your cells.
- Insulin lowers the amount of sugar in your bloodstream.
- As your blood sugar level drops, so does the secretion of insulin from your pancreas.
The role of glucose
Glucose — a sugar — is a main source of energy for the cells that make up muscles and other tissues.
- Glucose comes from two major sources: food and your liver.
- Sugar is absorbed into the bloodstream, where it enters cells with the help of insulin.
- Your liver stores glucose as glycogen.
- When your glucose levels are low, such as when you haven't eaten in a while, the liver converts stored glycogen into glucose to keep your glucose level within a normal range.
In type 1 diabetes, there's no insulin to let glucose into the cells, so sugar builds up in your bloodstream, where it can cause life-threatening complications.
The cause of type 1 diabetes is different from the cause of the more familiar type 2 diabetes. In type 2 diabetes, the islet cells are still functioning, but the body becomes resistant to insulin or the pancreas doesn't produce enough insulin or both.
Some known risk factors for type 1 diabetes include:
- Family history. Anyone with a parent or sibling with type 1 diabetes has a slightly increased risk of developing the condition.
- Genetics. The presence of certain genes indicates an increased risk of developing type 1 diabetes.
- Geography. The incidence of type 1 diabetes tends to increase as you travel away from the equator. People living in Finland and Sardinia have the highest incidence of type 1 diabetes — about two to three times higher than rates in the United States and 400 times the incidence among people living in Venezuela.
- Age. Although type 1 diabetes can appear at any age, it appears at two noticeable peaks. The first peak occurs in children between 4 and 7 years old, and the second is in children between 10 and 14 years old.
Many other possible risk factors for type 1 diabetes have been investigated, though none have been proved. Some other possible risk factors include:
- Exposure to certain viruses, such as the Epstein-Barr virus, Coxsackie virus, mumps virus and cytomegalovirus
- Early exposure to cow's milk
- Low vitamin D levels
- Drinking water that contains nitrates
- Early (before 4 months) or late (after 7 months) introduction of cereal and gluten into a baby's diet
- Having a mother who had preeclampsia during pregnancy
- Being born with jaundice
Type 1 diabetes can affect major organs in your body, including heart, blood vessels, nerves, eyes and kidneys. Keeping your blood sugar level close to normal most of the time can dramatically reduce the risk of many complications.
Long-term complications of type 1 diabetes develop gradually, over decades. Good blood sugar management can help lower the risk of complications. Eventually, diabetes complications may be disabling or even life-threatening.
- Heart and blood vessel disease. Diabetes dramatically increases your risk of various cardiovascular problems, including coronary artery disease with chest pain (angina), heart attack, stroke, narrowing of the arteries (atherosclerosis) and high blood pressure.
Nerve damage (neuropathy). Excess sugar can injure the walls of the tiny blood vessels (capillaries) that nourish your nerves, especially in the legs. This can cause tingling, numbness, burning or pain that usually begins at the tips of the toes or fingers and gradually spreads upward. Poorly controlled blood sugar could cause you to eventually lose all sense of feeling in the affected limbs.
Damage to the nerves that affect the gastrointestinal tract can cause problems with nausea, vomiting, diarrhea or constipation. For men, erectile dysfunction may be an issue.
- Kidney damage (nephropathy). The kidneys contain millions of tiny blood vessel clusters that filter waste from your blood. Diabetes can damage this delicate filtering system. Severe damage can lead to kidney failure or irreversible end-stage kidney disease, which requires dialysis or a kidney transplant.
- Eye damage. Diabetes can damage the blood vessels of the retina (diabetic retinopathy), potentially leading to blindness. Diabetes also increases the risk of other serious vision conditions, such as cataracts and glaucoma.
- Foot damage. Nerve damage in the feet or poor blood flow to the feet increases the risk of various foot complications. Left untreated, cuts and blisters can become serious infections, which often heal poorly and may ultimately require toe, foot or leg amputation.
- Skin and mouth conditions. Diabetes may leave you more susceptible to skin problems, including bacterial and fungal infections.
- Pregnancy complications. High blood sugar levels can be dangerous for both the mother and the baby. The risk of miscarriage, stillbirth and birth defects are increased when diabetes isn't well-controlled. For the mother, diabetes increases the risk of diabetic ketoacidosis, diabetic eye problems (retinopathy), pregnancy-induced high blood pressure and preeclampsia.
There's no known way to prevent type 1 diabetes. But researchers are working on preventing the disease or further destruction of the islet cells in people who are newly diagnosed. Ask your doctor if you might be eligible for one of these clinical trials, but carefully weigh the risks and benefits of any treatment available in a trial.
You can find more information on the types of research being done from TrialNet, a collaboration of diabetes researchers. TrialNet is also conducting a natural history study to check for diabetes genes in parents, children and siblings of people with type 1 diabetes.