What is metformin?Thursday, 1 March 2018
Metformin is the first drug of choice in the treatment of high blood glucose levels in adults and children over 10 years of age with type 2 diabetes. It is also used for people with gestational diabetes and polycystic ovary syndrome. It is especially useful for people who are overweight or obese, when diet and exercise are not enough to lower high blood glucose levels.
How it works
In adults, Metformin can be used alone, or in combination with other oral diabetes medications, or in combination with insulin. It works on both fasting blood glucose levels as well as after meals, by lowering the amount of glucose made by the liver, which in turn makes the body’s cells more sensitive to the action of insulin, and delays the uptake of glucose by the gut. All this without increasing risk of hypoglycaemia (low blood glucose levels). It may also lower cholesterol and triglycerides, and promote a small amount of weight loss. Hypoglycaemia is extremely rare when Metformin is used on its own.
How to take it
Metformin should be started at a low dose (500 mg/day), and always taken during or immediately after meals (with a glass of water), at about the same time each day. This will reduce the risk of gastrointestinal adverse effects and help you to remember to take it. The dose may be increased slowly depending on blood glucose levels.
Side effects can include nausea, vomiting, abdominal bloating and pain, diarrhoea and anorexia. These often subside within a few weeks, but can persist in some people. If they become intolerable, see your doctor before making any changes. Side effects are less likely with the extended-release formulation, which was developed to minimise side effects and improve absorption and tolerability. It is taken once a day, which may make it easier to remember for some individuals.
Another side effect of Metformin is a vitamin B12 deficiency in some people, especially in the elderly. A yearly blood test is recommended, and treatment if levels are below the target range.
Metformin is very useful long term, and is stopped only in certain circumstances, such as kidney failure, severe liver disease, moderate to severe heart failure, diabetic ketoacidosis (a symptom of unmanaged diabetes, in which substances called ketones build up in the blood – you may notice this as a fruity odour on your breath, difficulty breathing, confusion and frequent urination), or if you are currently breastfeeding, or plan to breastfeed.
It is stopped temporarily before and after major surgery, or an examination requiring a contrast injection or dye. It’s important that you follow your doctor’s instructions closely.
And lastly, as with all medications, speak with your doctor before you make any changes to the type, dose or time that you take your medications.
If you have any questions about your diabetes management, including your medications, speak with your doctor or pharmacist, or call the Diabetes NSW & ACT info line on 1300 342 238 and ask to speak with a diabetes educator.