Diabetes is a group of diseases in which your blood has too much glucose (sugar) in it, which can cause many serious health problems. Diabetes treatment depends on the cause of the diabetes.

Diabetes Overview

Reviewed: May 19, 2014

Diabetes mellitus (DM or, simply, diabetes) refers to a group of diseases that affect how your body uses sugar (glucose). Glucose comes from the foods you eat. Glucose is essential to health because it is an important source of energy for the cells that make up your muscles and tissues and it is the brain's main source of fuel. If you have diabetes, no matter what type, it means you have too much glucose in your blood, although the causes may differ. Too much glucose can lead to serious health problems.

Insulin is a hormone that helps the glucose get into your cells to give them energy. With type 1 diabetes, your body does not make insulin. With type 2 diabetes, the more common type, your body does not make or use insulin well. Without enough insulin, the glucose stays in your blood. Although type 1 diabetes can develop at any age, it typically appears during childhood or adolescence. Type 2 diabetes, the more common type, can develop at any age, though it is more common in people older than 40.

Potentially reversible diabetes conditions include prediabetes — when blood sugar levels are higher than normal, but not high enough to be classified as diabetes — and gestational diabetes, which occurs during pregnancy but may resolve after the baby is delivered.

Over time, having too much glucose in your blood can cause serious problems. Diabetes can lead to damage of your eyes, kidneys, and nerves, and it can cause heart disease and stroke.

A blood test can show if you have diabetes. Exercise, weight control, and sticking to your meal plan can help control your diabetes. Treatments will vary depending on the type of diabetes you have.

Diabetes Symptoms

Diabetes symptoms vary depending on how much your blood sugar is elevated. Some people, especially those with prediabetes or type 2 diabetes, may have symptoms so mild that they go unnoticed. In type 1 diabetes, symptoms tend to come on quickly and be more severe.

Some of the signs and symptoms of type 1 and type 2 diabetes are:

  • Urinating often
  • Feeling very thirsty
  • Feeling very hungry - even though you are eating
  • Extreme fatigue
  • Irritability
  • Blurry vision
  • Cuts and/or bruises that are slow to heal
  • Frequent infections
  • Weight loss - even though you are eating more (type 1)
  • Tingling, pain, or numbness in the hands/feet (type 2)

Diabetes Causes

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

Insulin is a hormone that comes from a gland situated behind and below the stomach (pancreas). The pancreas secretes insulin into the bloodstream and the insulin circulates, allowing glucose (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.

Glucose is a source of energy for the cells that make up muscles and other tissues. Glucose comes from 2 major sources: food and your liver. Sugar is absorbed into the bloodstream, where it enters cells with the help of insulin. Your liver stores and makes glucose. When your glucose levels are low, such as when you have not eaten in a while, the liver breaks down stored glycogen into glucose to keep your glucose level within a normal range.

Type 1 and type 2 diabetes are conditions characterized by high blood glucose levels caused by either a lack of insulin (type 1) or the body's inability to use insulin efficiently (type 2). Two factors are important in the development of both type 1 and type 2 diabetes: a predisposition to the disease is inherited and then something in your environment triggers the onset of the disease.

The exact cause of type 1 diabetes is unknown. What is known is that your immune system attacks and destroys your 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. Type 1 diabetes is thought to be caused by a combination of genetic susceptibility and environmental factors, though exactly what many of those factors are is still unclear. One trigger might be related to cold weather. Type 1 diabetes develops more often in winter than summer and is more common in places with cold climates. Another trigger might be viruses. Perhaps a virus that has only mild effects on most people triggers type 1 diabetes in others. Early diet may also play a role. Type 1 diabetes is less common in people who were breastfed and in those who first ate solid foods at later ages.

Type 2 diabetes has a stronger link to family history and lineage than type 1, although it too depends on environmental factors.

In prediabetes — which can lead to type 2 diabetes — and in type 2 diabetes, your cells become resistant to the action of insulin, and your pancreas is unable to make enough insulin to overcome this resistance. Instead of moving into your cells where it is needed for energy, sugar builds up in your bloodstream.

Exactly why this happens is uncertain, although it is believed that genetic and environmental factors play a role in the development of type 2 diabetes. Being overweight is strongly linked to the development of type 2 diabetes, but not everyone with type 2 is overweight.

During pregnancy, the placenta produces hormones to sustain your pregnancy. These hormones make your cells more resistant to insulin. Normally, your pancreas responds by producing enough extra insulin to overcome this resistance. But sometimes your pancreas cannot keep up. When this happens, too little glucose gets into your cells and too much stays in your blood, resulting in gestational diabetes. This condition is often reversible after the baby is delivered.

Diabetes Diagnosis

Several blood tests are used to screen for and diagnosis diabetes:

  • Glycated hemoglobin (A1C) test. This blood test indicates your average blood sugar level for the past 2 to 3 months. It measures 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 have with sugar attached. An A1C level of 6.5 percent or higher on 2 separate tests indicates that you have diabetes. An A1C between 5.7 and 6.4 percent indicates prediabetes. Below 5.7 is considered normal.
  • 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) — 11.1 millimoles per liter (mmol/L) — or higher suggests diabetes.
  • Fasting blood sugar test. A blood sample will be taken after an overnight fast. A fasting blood sugar level less than 100 mg/dL (5.6 mmol/L) is normal. A fasting blood sugar level from 100 to 125 mg/dL (5.6 to 6.9 mmol/L) is considered prediabetes. If it's 126 mg/dL (7 mmol/L) or higher on two separate tests, you have diabetes.
  • Oral glucose tolerance test. For this test, you fast overnight, and the fasting blood sugar level is measured. Then you drink a sugary liquid, and blood sugar levels are tested periodically for the next two hours. A blood sugar level less than 140 mg/dL (7.8 mmol/L) is normal. A reading of more than 200 mg/dL (11.1 mmol/L) after two hours indicates diabetes. A reading between 140 and 199 mg/dL (7.8 mmol/L and 11.0 mmol/L) indicates prediabetes.

Living With Diabetes

Diabetes is a serious disease. Following your diabetes treatment plan takes round-the-clock commitment. Careful management of diabetes can reduce your risk of serious and life-threatening complications.

Make a commitment to managing your diabetes. Learn all you can about diabetes. Establish a relationship with a diabetes educator, and ask your diabetes treatment team for help when you need it.

Choose healthy foods and maintain a healthy weight. A healthy diet is one with plenty of fruits, vegetables, whole grains and legumes, with a limited amount of saturated fat.

Make physical activity part of your daily routine. Regular exercise can help prevent prediabetes and type 2 diabetes, and it can help those who already have diabetes to maintain better blood sugar control. Lifestyle for type 1 and type 2 diabetes

You should also:

  • Identify yourself. Wear a tag or bracelet that says you have diabetes. Keep a glucagon kit nearby in case of a low blood sugar emergency and make sure your friends and loved ones know how to use it.
  • Schedule a yearly physical and regular eye exams. Your regular diabetes checkups are not meant to replace yearly physicals or routine eye exams. During the physical, your doctor will look for any diabetes-related complications and screen for other medical problems. Your eye care specialist will check for signs of retinal damage, cataracts and glaucoma.
  • Keep your vaccinations up to date. High blood sugar can weaken your immune system. Get a flu shot every year, and your doctor may recommend the pneumonia vaccine, as well. The Centers for Disease Control and Prevention (CDC) also currently recommends hepatitis B vaccination if you haven't previously been vaccinated against hepatitis B and you are an adult ages 19 to 59 with type 1 or type 2 diabetes. The most recent CDC guidelines advise vaccination as soon as possible after diagnosis with type 1 or type 2 diabetes. If you are age 60 or older, have diabetes, and haven't previously received the vaccine, talk to your doctor about whether it's right for you.
  • Pay attention to your feet. Wash your feet daily in lukewarm water. Dry them gently, especially between the toes. Moisturize with lotion, but not between the toes. Check your feet every day for blisters, cuts, sores, redness or swelling. Consult your doctor if you have a sore or other foot problem that does not heal promptly on its own.
  • Keep your blood pressure and cholesterol under control. Eating healthy foods and exercising regularly can go a long way toward controlling high blood pressure and cholesterol. Medication may be needed, too.
  • Take care of your teeth. Diabetes may leave you prone to serious gum infections. Brush and floss your teeth at least twice a day. And if you have type 1 or type 2 diabetes, schedule regular dental exams. Consult your dentist right away if your gums bleed or look red or swollen.
  • If you smoke or use other types of tobacco, ask your doctor to help you quit. Smoking increases your risk of various diabetes complications. Smokers who have diabetes are more likely to die of cardiovascular disease than are nonsmokers who have diabetes, according to the American Diabetes Association. Talk to your doctor about ways to stop smoking or to stop using other types of tobacco.
  • If you drink alcohol, do so responsibly. Alcohol can cause either high or low blood sugar, depending on how much you drink and if you eat at the same time. If you choose to drink, do so only in moderation and always with food. Remember to include the carbohydrates from any alcohol you drink in your daily carbohydrate count. And check your blood sugar levels before going to bed.
  • Take stress seriously. The hormones your body may produce in response to prolonged stress may prevent insulin from working properly, which will raise your blood sugar and stress you even more. Set limits for yourself and prioritize your tasks. Learn relaxation techniques. And get plenty of sleep.

Long-term complications of diabetes develop gradually. The longer you have diabetes and the less controlled your blood sugar the higher the risk of complications. Eventually, diabetes complications may be disabling or even life-threatening. Possible complications include:

  • Cardiovascular disease. Diabetes dramatically increases the risk of various cardiovascular problems, including coronary artery disease with chest pain (angina), heart attack, stroke, and narrowing of arteries (atherosclerosis). If you have diabetes, you are more likely to have heart disease or stroke.
  • Nerve damage (neuropathy). Excess sugar can injure the walls of the tiny blood vessels (capillaries) that nourish your nerves, especially in your legs. This can cause tingling, numbness, burning or pain that usually begins at the tips of the toes or fingers and gradually spreads upward. Left untreated, you could lose all sense of feeling in the affected limbs. Damage to the nerves related to digestion can cause problems with nausea, vomiting, diarrhea or constipation. For men, it may lead to erectile dysfunction.
  • Kidney damage (nephropathy). The kidneys contain millions of tiny blood vessel clusters (glomeruli) 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 may require dialysis or a kidney transplant.
  • Eye damage (retinopathy). 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 develop serious infections, which often heal poorly. These infections may ultimately require toe, foot or leg amputation.
  • Skin conditions. Diabetes may leave you more susceptible to skin problems, including bacterial and fungal infections.
  • Hearing impairment. Hearing problems are more common in people with diabetes.
  • Alzheimer's disease. Type 2 diabetes may increase the risk of Alzheimer's disease. The poorer your blood sugar control, the greater the risk appears to be. Although there are theories as to how these disorders might be connected, none has yet been proved.

Diabetes Treatments

Depending on what type of diabetes you have, blood sugar monitoring, insulin, and oral medications may play a role in your treatment. Eating a healthy diet, maintaining a healthy weight, and participating in regular activity also are important factors in managing diabetes.

Treatment for type 1 diabetes involves insulin injections or the use of an insulin pump, frequent blood sugar checks, and carbohydrate counting. Treatment of type 2 diabetes primarily involves monitoring of your blood sugar, along with diabetes medications, insulin or both.

  • Monitoring your blood sugar. Depending on your treatment plan, you may check and record your blood sugar as often as several times a week to as many as four to eight times a day. Careful monitoring is the only way to make sure that your blood sugar level remains within your target range. People who receive insulin therapy also may choose to monitor their blood sugar levels with a continuous glucose monitor. Although this technology doesn't yet replace the glucose meter, it can provide important information about trends in blood sugar levels. Even with careful management, blood sugar levels can sometimes change unpredictably. With help from your diabetes treatment team, you'll learn how your blood sugar level changes in response to food, physical activity, medications, illness, alcohol, stress, and, especially for women, fluctuations in hormone levels. In addition to daily blood sugar monitoring, your doctor will likely recommend regular A1C testing to measure your average blood sugar level for the past two to three months. Compared with repeated daily blood sugar tests, A1C testing better indicates how well your diabetes treatment plan is working overall. An elevated A1C level may signal the need for a change in your insulin regimen or meal plan. Your target A1C goal may vary depending on your age and various other factors. However, for most people with diabetes, the American Diabetes Association recommends an A1C of below 7 percent. Ask your doctor what your A1C target is.
  • Insulin. People with type 1 diabetes need insulin therapy to survive. Many people with type 2 diabetes or gestational diabetes also need insulin therapy. Many types of insulin are available, including rapid-acting insulin, long-acting insulin and intermediate options. Depending on your needs, your doctor may prescribe a mixture of insulin types to use throughout the day and night. Insulin is usually injected using a fine needle and syringe or an insulin pen — a device that looks like a large ink pen. An insulin pump may also be an option. The pump is a device about the size of a cellphone worn on the outside of your body. A tube connects the reservoir of insulin to a catheter that's inserted under the skin of your abdomen. A tubeless pump that works wirelessly is also now available. You program an insulin pump to dispense specific amounts of insulin. It can be adjusted to deliver more or less insulin depending on meals, activity level and blood sugar level.
  • Oral or other medications. Sometimes other oral or injected medications are prescribed as well. Some diabetes medications stimulate your pancreas to produce and release more insulin. Others inhibit the production and release of glucose from your liver, which means you need less insulin to transport sugar into your cells. Still others block the action of stomach or intestinal enzymes that break down carbohydrates or make your tissues more sensitive to insulin. Metformin (Glucophage, Glumetza, others) is generally the first medication prescribed for type 2 diabetes.
If you have prediabetes, healthy lifestyle choices can help you bring your blood sugar level back to normal or at least keep it from rising toward the levels seen in type 2 diabetes. Maintaining a healthy weight through exercise and healthy eating can help. Exercising at least 150 minutes a week and losing 5 to 10 percent of your body weight may prevent or delay type 2 diabetes.

Diabetes Prognosis