What's new in diabetes care
Introduction to diabetes
Types of diabetes
Diagnosis
Risk factors & screening

Oral medications

Different groups of anti-diabetic drugs

• Sulphonylureas
• Meglitinide e.g Repaglinide, Nateglinide
• Biguanides
• alpha-glucosidase inhibitor, e.g. Acarbose
• Thiazolidinediones (Glitazones)

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Different groups of anti-diabetic drugs

Different groups of diabetes medications work in different ways. Some patients may need more than one type of medications to control blood glucose well.

There are 4 main groups of oral anti-diabetic drugs available in the market:

Sulphonylureas

Sulphonylureas lower blood glucose levels by increasing the release of insulin from the pancreas. Older generations of these drugs include chlorpropamide and tolbutamide, while newer drugs include Glibenclamide (Daonil), gliclazide (Diamicron), glipizide (Minidiab), and glimepiride (Amaryl). They are effective in rapidly lowering blood glucose, but run the risk of causing hypoglycaemia. They are sulpha compounds, and should be avoided in patients with sulpha allergies.

Meglitinide e.g Repaglinide, Nateglinide

This is a new non-sulphonylurea insulin secretagogue. It works on pancreas to promote insulin secretion, but through a separate K+ channel on the cell surface (sulphonylureas bind to receptors on the insulin producing cells). This group of drugs are short acting agents with peak effects within one hour, hence can reduce postprandial hyperglycaemia. It must be taken 15-30 min before each meal. There is no further benefit if combine with sulphonylureas.

Biguanides

Biguanides e.g. Metformin do not stimulate insulin secretion. Monotherapy with metformin does not cause hypoglycaemia. Metformin decreases hyperglycaemia in type 2 diabetic patients but does not lower blood glucose levels in non-diabetic individuals. It has its most dramatic effect in decreasing fasting hyperglycaemia. Treatment with Metformin results in either a moderate weight loss or no weight gain. It is now the first line drug for type 2 diabetes especially if patients are also overweight or obese. However it should not be used in patients with kidney failure, liver disease and heart failure

Alpha-glucosidase inhibitor, e.g. Acarbose

By inhibiting α-glucosidase, carbohydrates are not broken down as efficiently and glucose absorption is delayed. It is useful in those with normal fasting glucose and high postprandial glucose levels. It is taken 3 times a day at the beginning of meals. The main concern is that up to 75% of patients complain of abdominal pain, diarrhoea or flatulence

Thiazolidinediones (Glitazones)

Glitazones lower blood glucose by improving target cell response to insulin (increasing the sensitivity of the cells to insulin i.e. insulin sensitiser). Troglitazone, the first of this type of compound, has been taken off the market because of severe toxic liver effects. Newer sister compounds including rosiglitazone (Avandia) and pioglitazone (Actos) with a better safety profile are now available. They act within one hour of administration and can be taken once daily. It takes up to 6 weeks to see a drop in blood glucose levels on these agents and up to 12 weeks to see a maximum benefit. They have added benefit of changing cholesterol pattern e.g raised HDL and decrease triglyceride. Side effects include fluid retention. Patients with heart failure are advised not to take these drugs.

Summary of the effect of different class of anti-diabetic drugs on blood glucose

The table below shows the summary of effect of different class of anti-diabetic drugs on blood glucose: