If regular exercise and a healthy diet are not effective in controlling your blood glucose levels, you may need medicines to treat type 2 diabetes.
Several different types of medicine, usually taken as tablets, are used to treat type 2 diabetes. You may need to take a combination of two or more medicines to control your blood glucose level.
Metformin is often the first medicine that is recommended to treat type 2 diabetes. It works by reducing the amount of glucose that your liver releases into your bloodstream. It also makes your body's cells more responsive to insulin.
If you are overweight, it is likely that you will be prescribed metformin. Unlike some other medicines that are used to treat type 2 diabetes, metformin should not cause additional weight gain. However, it can sometimes cause mild side effects, such as nausea and diarrhoea and you may not be able to take it if you have kidney damage.
Sulphonylureas increase the amount of insulin that is produced by your pancreas. Examples of sulphonylureas include:
You may be prescribed one of these medicines if you cannot take metformin or if you are not overweight. You may be prescribed a sulphonylurea and metformin if metformin does not control blood glucose on its own.
Sulphonylureas can increase the risk of hypoglycaemia (low blood glucose) because they increase the amount of insulin in your body. Sulphonylureas may sometimes cause side effects including weight gain, nausea and diarrhoea.
Glitazones (thiazolidinediones, TZDs)
Thiazolidinedione medicines (pioglitazone) make your body’s cells more sensitive to insulin so that more glucose is taken from your blood. They are not often used alone, but are usually used in addition to metformin or sulphonylureas, or both. They may cause weight gain and ankle swelling. Do not take pioglitazone if you have heart failure or if you have a high risk of bone fracture.
Another thiazolidinedione, rosiglitazone, has been withdrawn from use because of the increased risk of cardiovascular disorders, including heart attack and heart failure. If you are currently taking rosiglitazone, you should continue to take the medicine as prescribed. You should also make an appointment to see your healthcare team to discuss alternative medication.
Gliptins (DPP-4 inhibitors)
Gliptins work by preventing the breakdown of a naturally occurring hormone called GLP-1. GLP-1 helps the body produce insulin in response to high blood glucose levels, but is rapidly broken down. By preventing this breakdown, the gliptins (sitagliptin and vildagliptin) act to prevent high blood glucose levels, but do not result in episodes of hypoglycaemia. You may be prescribed a gliptin if you are unable to take sulphonylureas or glitazones. They are not associated with weight gain.
Exenatide is a GLP-1 agonist, an injectable treatment that acts in a similar way to the natural hormone GLP-1 (see section on gliptins, above). It is injected twice a day and boosts insulin production when there are high blood glucose levels, reducing blood glucose without the risk of hypoglycaemic episodes ('hypos'). It also leads to modest weight loss in many people who take it. It is mainly used in people on metformin plus sulphonylurea who are obese (with a BMI of 35 or above).
Another GLP-1 agonist called liraglutide has recently been launched in the UK. It is a once daily injection (exenatide is given twice a day). Like exenatide, it is mainly used in people on metformin plus sulphonylurea who are obese, and in clinical trials it has been shown to cause modest weight loss.
Acarbose helps prevent your blood glucose level from increasing too much after you eat a meal. It slows down the rate at which your digestive system breaks carbohydrates down into glucose.
Acarbose is not often used to treat type 2 diabetes because it usually causes side effects, such as bloating and diarrhoea. However, you may be prescribed acarbose if you cannot take other types of medicine for type 2 diabetes.
Nateglinide and repaglinide
Nateglinide and repaglinide stimulate the release of insulin by your pancreas. They are not commonly used but may be an option if you have meals at irregular times. This is because their effects do not last very long, but they are effective when taken just before you eat.
Nateglinide and repaglinide can cause side effects, such as weight gain and hypoglycaemia (low blood glucose).
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