COMBINATIONS OF ORAL DRUGS
Since these drugs have different mechanisms of action, their combinations are often effective when one drug is ineffective. Mixtures of a Sulphonylurea, metformin and a thiazolidinedione have been marketed in different permutation and combination, too many to be listed here.
Thiazolidinediones
Actions
These drugs are called 'insulin sensitizers'. They reduce insulin resistance in type 2 diabetes, reduce production of glucose by liver and increase disposal of glucose.
Doses
Rosiglitazone may be given in a daily dose of upto 8 mg, usually in divided doses with or without food.
Pioglitazone is given in the dose of 15-45 mg/day, in single dose Uses
They are given in combination with sulphonylureas or metformin or alone. They are not combined with insulin and are not given in children, pregnancy or with impaired liver and cardiac (heart) function.
Side effects
These drugs may give rise to nausea, vomiting, fullness of abdomen, swelling of the body, anemia, diarrhoea, liver failure, affection of heart muscle. They can lead to irreversible weight gain, hence weight should be closely monitored while on these drugs.
Periodic monitoring of liver function is advisable while on these drugs. Women who were previously not ovulating (giving out egg) may start doing so, hence effective contraception is necessary if pregnancy is to be avoided. These drugs are contraindicated in pregnancy or lactation.
Guar gum
This is a gum obtained from plants e.g. guar. It slows absorption of glucose from small intestine and thus reduces rise in blood glucose after meals. Marketed as powder, it is sprinkled on food or taken with 200 ml of water, in the dose of 5 g three times a day. Side effects are fullness and distension of abdomen and intestinal obstruction.
Diet and exercise
Diet and exercise is the sheet anchor of the treatment of type 2 diabetes. Many persons with type 2 diabetes are obese. Their diabetes can be controlled by weight reduction.
These oral drugs do not allow a diabetic to dispense with his/her diet. An excess of food will make a diabetic obese and ultimately impair efficacy of these drugs. A person taking a sulphonulurea drug may develop hypoglycaemia if meals are delayed or skipped. Oral drugs are not a substitute for a diabetic diet and exercise.
Oral drugs
In type 2 diabetes, there is beta cell failure and insulin resistance to a varying extent, Insulin resistance is present in obese persons. Metformin or thiazolidinediones are indicated in these subjects. Beta cell failure is a feature of thin patients. In these subjects, sulphonylureas or meglitinide group of drugs are indicated.
Oral drugs are given in small dose initially. Their dose is increased gradually, according to response. By the time type 2 diabetes is detected, beta cell function is already diminished by 50 per cent. Every year, the beta cell function diminishes by 4 per cent. It is obvious therefore that many oral drugs, effective in early stages of the disease become ineffective in later stages. Hence new drugs or their combinations will have to be introduced, with passage of time. Ultimately, insulin becomes inevitable when there is gross beta cell failure.
Control of blood pressure, serum lipids and cessation of consumption of tobacco are important for prevention of blood vessel disease. This is achieved by different oral drugs.
Blood tests
An estimation of blood glucose levels, fasting and two hours after lunch (with usual drug) should be carried out at least once in three months. HbAlc test is useful to assess over all control of diabetes. A regular check up is also essential. As time passes, these drugs tend to lose their efficacy. This delayed failure of drugs will be overlooked if blood tests are not carried out regularly.
A changeover from an oral drug to insulin is necessary in case of severe infection, if the person has to undergo a major operation, when it is obvious that the oral drugs are not working or not likely to work. It is unwise and even dangerous to persist with the oral drugs when they have ceased to act.
The targets of treatment should be pragmatic. It is now established that maintaining normoglycaemia prevents complications of diabetes. While one aims at near normal blood glucose levels and HbAlc near or below 7.0, severe hypoglycaemia should be avoided.
Use of drugs on non-medical advice
Reports of drugs effective in diabetes, usually of an indigenous origin, appear from time to time. Most of these reports are unscientific. Many diabetics, on the basis of such reports or on the suggestion of their well meaning but poorly informed neighbours or friends, are tempted to try these drugs. The control of diabetes, achieved after a long and a careful treatment is undone by changing over to such "remedies" or "cures" of diabetes. A golden rule for a diabetic is never to omit a drug or try another drug without competent medical advice.