Type 1 diabetes

Introduction

Type 1 diabetes, once known as juvenile diabetes or insulin-dependent diabetes, is a chronic condition in which the pancreas produces little or no insulin, a hormone needed to convert sugar (glucose) into energy. Although type 1 diabetes can develop at any age, it typically appears during childhood or adolescence.

Type 2 diabetes is a similar — although much more common — condition in which the body becomes resistant to the effects of insulin or the body produces some, but not enough, insulin to maintain a normal blood sugar level.

Various factors may contribute to type 1 diabetes, including genetics and exposure to certain viruses. Despite active research, type 1 diabetes has no cure. But advances in blood sugar monitoring and insulin delivery have simplified the daily routine of managing type 1 diabetes. With proper treatment, people who have type 1 diabetes can expect to live long, healthy lives.

Signs and symptoms

Type 1 diabetes symptoms may seem harmless at first. Look for:

• Increased thirst and frequent urination. As excess sugar builds up in your bloodstream, fluid is pulled from your tissues. This may leave you thirsty. As a result, you may drink — and urinate — more than usual.
• Extreme hunger. Without enough insulin to move sugar into your cells, your muscles and organs become depleted of energy. This triggers intense hunger that may persist even after you eat. Without insulin, the sugar in your food never reaches your energy-starved tissues.
• Weight loss. Despite eating more than usual to relieve hunger, you may lose weight — sometimes rapidly. Without the energy sugar supplies, your muscle tissues and fat stores may simply shrink.
• Fatigue. If your cells are deprived of sugar, you may become tired and irritable.
• Blurred vision. If your blood sugar level is too high, fluid may be pulled from your tissues — including the lenses of your eyes. This may affect your ability to focus clearly.

Causes

To understand type 1 diabetes, first you must understand how glucose is normally processed in the body.

Glucose is a main source of energy for the cells that make up your muscles and other tissues. Glucose comes from two major sources: the food you eat and your liver. During digestion, sugar is absorbed into the bloodstream. Normally, sugar then enters cells with the help of insulin.

The hormone insulin comes from the pancreas, a gland located just behind the stomach. When you eat, your pancreas secretes insulin into your bloodstream. As insulin circulates, it acts like a key by unlocking microscopic doors that allow 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.

Your liver acts as a glucose storage and manufacturing center. When your insulin levels are low — when you haven't eaten in a while, for example — your liver releases the stored glucose to keep your glucose level within a normal range.

In type 1 diabetes, your immune system — which normally fights harmful bacteria or viruses — attacks and destroys the insulin-producing cells in the pancreas. This leaves you with little or no insulin. Instead of being transported into your cells, sugar builds up in your bloodstream.

The exact cause of type 1 diabetes is unknown. Genetics may play a role. Exposure to certain viruses may serve as a trigger as well.

Risk factors

Although the exact cause of type 1 diabetes is unknown, family history may play a role. Your risk of developing type 1 diabetes increases if you have a parent or sibling who has type 1 diabetes.

Screening and diagnosis

Various blood tests can be used to screen for diabetes, including:

• Random blood sugar test. A blood sample will be taken at a random time. Regardless of when you last ate, a random blood sugar level of 200 milligrams per deciliter (mg/dL) or higher suggests diabetes.
• Fasting blood sugar test. A blood sample will be taken after an overnight fast. A fasting blood sugar level between 70 and 100 mg/dL is normal. A fasting blood sugar level from 100 to 125 mg/dL is considered prediabetes, which indicates a high risk of developing diabetes. If it's 126 mg/dL or higher on two separate tests, you'll be diagnosed with diabetes.

If you're diagnosed with diabetes, your doctor may do other tests to distinguish between type 1 and type 2 diabetes — which may require different treatment strategies. Type 1 diabetes might be suspected if you have little or no ability to produce insulin, you have antibodies to insulin-producing cells in your blood, or you have toxic acids produced by the breakdown of fat (ketones) in your urine.

If you're diagnosed with diabetes, your doctor may also recommend a glycated hemoglobin (A1C) test. This blood test indicates your average blood sugar level for the past two to three months. It works by measuring the percentage of blood sugar attached to hemoglobin, the oxygen-carrying protein in red blood cells. The higher your blood sugar levels, the more hemoglobin you'll have with sugar attached. Generally, a target A1C result is 7 percent or less.