Diabetes Drugs

What are the types ?

nsulins may be short-acting (soluble), or modified to lengthen their action. There are 40 or more types available. Because insulin cannot be absorbed by the bowel, it must be given by injection. Much insulin is now made by genetic engineering methods; some is still extracted directly from pork or beef pancreas. There are several types of tablets. The sulphonylureas are tolbutamide, glibenclamide (Daonil, Euglucon), gliclazide (Diamicron), chlorpropamide, tolazamide (Tolanase), gliquidone (Glurenorm), glimepiride (Amaryl) and glipizide (Glibenese, Minodiab). The only biguanide is metformin (Glucophage). Acarbose (Glucobay) is also used. Guar gum (Guarem), repaglinide (Novonorm) and rosiglitazone (Avandia) are also used.

What are they for ?

They are only used to treat diabetes mellitus. Insulin is essential for so-called type 1 diabetes where the body cannot make insulin. In type 2 diabetes some insulin is still made, but not enough to satisfy the body's needs. If diet treatment alone is not fully effective, tablets are added. Sometimes insulin is also needed in type 2 diabetes.

How do they work ?

Insulin helps glucose to get into your body's cells. Inside the cells, insulin helps glucose to be changed into energy, and into other substances like proteins and fat. Sulphonylureas help the pancreas to make more insulin. They also help insulin to act on body cells. Metformin works on the cells directly, especially in muscles and liver. Insulin already there is helped to work better. Acarbose stops starches being converted to sugar in the bowel. Less sugar therefore gets into the body. Guar gum reduces absorption of carbohydrates after a meal. Repaglinide increases the body's own insulin supply and is sometimes given with another tablet such as metformin. Rosiglitazone helps the body's own insulin to work better by making the cells more sensitive to its actions. It is used together with metformin or a sulphonylurea. It can also be used with insulin injections, to improve their action.

How should they be used ?

Insulin injections are usually given at least twice a day, 15 to 30 minutes before meals. The best control of blood sugar is often achieved with short-acting insulin three times a day before main meals, with a long-acting insulin at breakfast or bed-time. Insulin can be given by syringe or by pens. In pens, insulin is loaded as cartridges just like with a fountain pen. Insulin can also be given by a pump either outside the body or implanted in it. Tablets are taken once to three times a day in type 2 diabetes when dieting alone is not enough. Follow the instructions that you have been given as to when to take your tablets in relation to meals : some should be taken before and others after meals. You should always take them regularly: not just when glucose in the blood or urine rises. Sometimes, your doctor will prescribe a combination of these drugs. This helps to improve control of the blood sugar level. Under no circumstances should you stop any drugs for diabetes unless your doctor advises it.

During Treatment …

You may need to increase doses of insulin or tablets if the blood or urine glucose levels rise. Such dose increases may be needed if you gain weight, eat more or are under stress. Bigger doses are often needed if you have an infection. You may need less insulin or tablets if you are exercising more. If you are not sure how to handle these problems, your doctor will advise how to change your own doses. You will need to adjust your doses of insulin or tablets to keep the blood glucose level as close as possible to the normal range. Insulin or sulphonylureas can lower your glucose level too far (below 2.2 mmol/l: 40 mg/dl). This causes hypoglycaemia (or "hypos"). Sweating, trembling, hunger, faintness and even coma may result. Regular meals and sometimes snacks are essential to reduce this risk. Let your doctor know if you get anything other than occasional or mild hypos. Always keep a supply of glucose such as Dextrosol or lump sugar in your pocket or bag. Any anti-diabetic tablets can cause stomach and bowel upset, usually diarrhoea. With both metformin and acarbose, these often lessen with continued use. If they persist, see your doctor. Acarbose and guar gum are particularly likely to give you a lot of wind. Occasionally the sulphonylureas can cause skin rashes or (yellow) jaundice: again, see your doctor if this happens. Metformin is not usually prescribed if you have kidney, liver or heart problems. It can then cause the serious condition of lactic acidosis. Chlorpropamide is also unsafe with kidney failure.

Drug Interference …

Alcohol can also worsen or even cause "hypos", if you eat too little. Both ACE inhibitors and beta-blockers, drugs used for blood pressure treatment, can lower blood glucose, which can be helpful or harmful. Beta-blockers can also worsen "hypos" if they occur. Water tablets (diuretics) and particularly steroids (cortisone-like tablets) can raise blood glucose, sometimes to very high levels. Doses of your anti-diabetic drug are likely to need increasing. Your doctor will guide you. Some antibiotics, anti-inflammation and antifungal drugs increase the effect of anti-diabetic tablets.

What if not taken ?

Stopping any type of anti-diabetic drug can be dangerous. Your blood glucose level would certainly rise, making you less resistant to infections. Symptoms of thirst and excessive urination may come back. Even without symptoms, prolonged high glucose levels can damage other organs, particularly the eyes, kidneys and nerves. Your blood-vessels are also more likely to get blocked by a blood clot causing a stroke or heart attack. If you stop insulin, you could become seriously ill and go into coma. If you miss even a single dose of insulin at the time of another illness, you may get quite ill.

General advice

In every case, diet remains important. Diabetes will be easier to control if you are not overweight. Any illness or new drug may affect control. Test your own glucose level more often with illness or with any change in medication. If control does change, and you are not confident of altering your own doses, ask your doctor promptly. Anti-diabetic tablets are not safe during pregnancy: you would need insulin. In low doses, oral drugs are safe during breast-feeding. If you have any questions not answered by this factsheet, please ask your doctor or pharmacist. Keep this factsheet handy in case you have to refer to it at a later date.