Diabeta

Definition

Antidiabetic drugs are medicines that help control blood sugar levels in people with diabetes mellitus (sugar diabetes).

Purpose

Diabetes mellitus is a disorder of metabolism, the processes through which the body uses food that has been broken down by digestion. Most food is broken down into a type of sugar called glucose, which the body can use for energy and growth. Glucose travels through the bloodstream to cells throughout the body. But glucose cannot enter the cells without the help of a hormone called insulin. Insulin is produced by the pancreas, a large gland beneath the stomach. In people with diabetes mellitus, the body does not have enough insulin to move the glucose into the cells. This may be because the pancreas does not produce enough insulin or because the cells do not respond to the insulin, even though plenty is produced. Either way, glucose builds up in the blood and passes out of the body in urine without ever having been used as fuel.

Untreated, diabetes can lead to very serious problems, including heart disease, kidney failure, blindness, nerve damage, and amputations. But with proper management, the risk of such problems can be greatly reduced. The management plan depends on the type of diabetes: insulin-dependent diabetes mellitus (IDDM) or noninsulin-dependent diabetes mellitus (NIDDM).

Insulin-dependent diabetes mellitus

In this type of diabetes, also known as Type 1 diabetes, the pancreas produces little or no insulin. People with this type of diabetes must take injections of insulin every day to stay alive. They must also eat properly, following a schedule that helps keep glucose levels in the blood from getting too high or too low, and they must closely monitor their blood sugar levels with blood or urine tests.

Noninsulin-dependent diabetes mellitus

People with this type of diabetes, also known as Type 2 diabetes, produce enough insulin, but their bodies are unable to use it. Often, this type of diabetes can be controlled through diet and exercise. When it cannot, insulin or drugs called oral hypoglycemics may be prescribed.

Description

In addition to insulin, which is taken by injection, four types of medications (oral hypoglycemics) are used to help control noninsulin-dependent diabetes mellitus. Each type of medicine helps lower blood sugar in a different way, and all are available only with a physician's prescription. Some patients may take the pills alone or combined with other pills; others may take pills plus insulin injections. The four types of oral hypoglycemics are:

• Sulfonylureas, such as glipizide (Glucotrol), glyburide (DiaBeta, Glynase, Micronase), chlorpropamide (Diabinese), and tolbutamide (Orinase)
• Biguanides, such as metformin (Glucophage)
• Alpha-glucosidase inhibitors, such as acarbose (Precose) and miglitol (Glyset)
• Thiazolidinediones, such as troglitazone (Rezulin).

The remainder of this entry deals only with sulfonylureas and insulin.

Recommended dosage

The recommended dosage depends on the type of antidiabetic drug. Check with the physician who prescribed the drug or the pharmacist who filled the prescription for the correct dosage. Always take antidiabetic drugs exactly as directed. Never take larger or more frequent doses, and do not stop taking the medicine even if symptoms of diabetes improve.

Patients who use insulin should be trained by a health care professional in the proper way to prepare and inject their insulin.

Precautions

Seeing a physician regularly while taking antidiabetic drugs is important, especially during the first few weeks. The physician will check to make sure the medicine is working as it should and will watch for unwanted side effects. The physician may also need to adjust the dosage or change medicines.

For this medicine to be effective, doses must be carefully balanced with meals and daily activity. Health care professionals can teach patients how to achieve this balance and what to do if blood sugar levels get too high or too low. Following all guidelines for diet, exercise, regular blood sugar testing, use of alcohol and tobacco, sick days, and preparation for emergencies is extremely important.

Antidiabetic drugs do not cure diabetes, but they do help keep the condition under control and reduce the risk of serious complications. People with diabetes may need to take this medicine for the rest of their lives.

Sulfonylureas may increase sensitivity to sunlight. While being treated with this medicine, avoid being in direct sunlight, especially between 10 a.m. and 3 p.m.; wear a hat and tightly woven clothing that covers the arms and legs; use a sunscreen with a skin protection factor (SPF) of at least 15; protect the lips with a sun block lipstick; and do not use tanning beds, tanning booths, or sunlamps.

People with diabetes should wear a medical identification necklace or bracelet at all times and should carry a medical ID card listing all their medicines.

Older people may be especially sensitive to the effects of sulfonylureas, especially when they are taking more than one type of antidiabetic medicine. In addition, the early signs of low or high blood sugar may not be as noticeable in older people.

Children who have not reached puberty may be particularly sensitive to the effects of insulin and are more likely to have their blood sugar levels drop too low.

Special conditions

People with certain medical conditions or who are taking certain other medicines can have problems if they take antidiabetic drugs. Before taking these drugs, be sure to let the physician know about any of these conditions:

Anyone who has ever had unusual or allergic reactions to any antidiabetic medicines, sulfonamides (sulfa drugs), or thiazide diuretics (a type of water pill) should let his or her physician know before taking antidiabetic medicines again. The physician should also be told about any allergies to foods, dyes, preservatives, or other substances.

Pregnancy

Uncontrolled diabetes during pregnancy can lead to birth defects and other problems in the baby. In general, it is easier to control blood sugar levels during pregnancy with insulin than with sulfonylureas. Women who become pregnant or plan to become pregnant while taking antidiabetic drugs should check with their physicians about the best way to control their blood sugar levels.

Women who want to breastfeed their babies should check with their physicians if they are using oral hypoglycemics. Some sulfonylureas are not recommended for use while breastfeeding, but others may be used. Insulin does not pass into breast milk and will not affect nursing babies whose mothers use it. However, women who are breastfeeding may need to adjust their insulin doses based on their glucose levels. They should check their blood sugar often to see if any changes are necessary.

Before using antidiabetic drugs, people with any of these medical problems should make sure their physicians are aware of their conditions:

• Heart disease. Some antidiabetic drugs cause the body to retain water, which can make heart problems worse.
• Kidney disease or liver disease. Doses may need to be adjusted because the medicine leaves the body more slowly than usual in people with kidney disease or liver disease.
• Overactive thyroid. If this condition is not controlled, the medicine may leave the body too quickly. Doses may need to be adjusted until the thyroid problem is under control.
• Any condition in which blood sugar is high or low or changes rapidly, such as severe injury or infection, surgery, high fever, hormonal changes in women, severe mental stress, or poor nutrition. Blood sugar may need to be tested more often, and different combinations of drugs and insulin may be necessary.
• Any condition that delays stomach emptying or the absorption of food, such as diarrhea, vomiting, intestinal blockage, or gastroparesis (slow stomach emptying). Blood sugar may need to be tested more often, and different combinations of drugs and insulin may be necessary.

Taking antidiabetic drugs with certain other drugs may affect the way the drugs work or may increase the chance of side effects. While taking antidiabetic drugs, do not take any other prescription or nonprescription (over-the-counter) drugs without first checking with a physician.

Side effects

Sulfonylureas have been reported to increase the risk of death from diseases of the heart and blood vessels. However, not all studies show this link, and some sulfonylureas actually seem to have a positive effect on these diseases. Furthermore, uncontrolled diabetes can also lead to heart and blood vessel disease. Anyone who takes sulfonylureas should discuss the risks and benefits with his or her physician.

If seizures (convulsions), fainting, or unconsciousness occur during treatment with sulfonylureas or insulin, get medical help immediately.

Too much insulin or sulfonylurea may cause weight gain or low blood sugar. Check with a physician as soon as possible if weight gain or any of these signs of low blood sugar occur:

• Anxiety
• Nervousness
• Confusion
• Concentration problems
• Behavior changes that resemble drunkenness
• Drowsiness (more than mild)
• Nightmares or fitful sleep
• Headache
• Blurred vision
• Slurred speech
• Cold sweats or cool, pale skin
• Extreme hunger
• Shakiness
• Unusual tiredness or weakness
• Nausea
• Fast heartbeat.

Other side effects of sulfonylureas, such as dizziness, mild drowsiness, heartburn, changes in taste, changes in appetite, mild nausea, vomiting, stomach pain, fullness or discomfort in the stomach, constipation, frequent urination or increased urine output, usually go away as the body adjusts to the drug and do not require medical treatment unless they continue.

Other side effects are possible when taking insulin or sulfonylureas. Anyone who has unusual symptoms after taking antidiabetic drugs should get in touch with his or her physician.

Interactions

Antidiabetic drugs may interact with a number of other medicines. When this happens, the effects of one or both of the drugs may change or the risk of side effects may be greater. For example:

• Alcohol may cause low blood sugar problems to last longer than they normally would. Also, people who drink alcohol while taking antidiabetic drugs may have uncomfortable flushing of the face, arms, and neck.
• Many types of medicine may increase the chance of low blood sugar when taken with antidiabetic drugs. Examples are aspirin and other salicylates; medicines such as cimetidine (Tagamet) and ranitidine (Zantac), used to treat ulcers and heartburn; antifungal drugs such as fluconazole (Diflucan), ketoconazole (Nizoral), and miconazole (Monistat i.v.); medicine for infections, such as chloramphenicol (Chloromycetin) and ciprofloxacin (Cipro); and quinine, used to treat malaria.
• Other types of drugs may increase the chance of high blood sugar when taken with antidiabetic drugs. Some drugs that may have this effect are: corticosteroids; lithium, used to treat bipolar disorder (manic-depressive illness); and thiazide diuretics (a type of water pill).
• Other drugs may cause either high or low blood sugar levels when taken with antidiabetic drugs. Among these drugs are: cyclosporine (Sandimmune), a medicine that suppresses the immune system; the blood pressure medicine guanethidine (Ismelin); monoamine oxidase inhibitors (MAO) such as Nardil or Parnate, used to treat conditions including depression and Parkinson's disease; and Pentamidine, used to treat Pneumocystis carinii pneumonia.

The list above does not include every drug that may interact with antidiabetic drugs. Be sure to check with a physician or pharmacist before combining antidiabetic drugs with any other prescription or nonprescription (over-the-counter) medicine.

Key Terms

Blood sugar

The concentration of glucose in the blood.

Glucose

A simple sugar that serves as the body's main source of energy.

Hormone

A substance that is produced in one part of the body, then travels through the bloodstream to another part of the body where it has its effect.

Metabolism

All the physical and chemical changes that occur in cells to allow growth and maintain body functions. These include processes that break down substances to yield energy and processes that build up other substances necessary for life.

Salicylates

A group of drugs that includes aspirin and related compounds. Salicylates are used to relieve pain, reduce inflammation, and lower fever.

Seizure

A sudden attack, spasm, or convulsion.

Further Reading

For Your Information

Periodicals

• Hingley, Audrey. "Diabetes Demands a Trial of Treatments." FDA Consumer, 31 (May-June 1997): 33.

  Organizations

• American Diabetes Association. ADA National Service Center, 1660 Duke Street, Alexandria, VA 22314. 800-232-3472. http://www.diabetes.org.
• National Diabetes Information Clearinghouse. 1 Information Way, Bethesda, MD 20892-3560. 301-654-3327. ndic@info.niddk.nih.gov.

  Other

• National Institute of Diabetes and Digestive and Kidney Diseases http://www.niddk.nih.gov.

Gale Encyclopedia of Medicine. Gale Research, 1999.