From the Guidelines
Metformin is the recommended first-line treatment for type 2 diabetes. This recommendation is based on the most recent and highest quality evidence, including the 2019 standards of medical care in diabetes, which states that metformin is the preferred initial pharmacologic agent for the treatment of type 2 diabetes 1. The usual maintenance dose of metformin ranges from 1000-2000 mg daily, divided into two doses with morning and evening meals.
Key Considerations for Metformin Use
- Metformin works by decreasing glucose production in the liver, reducing intestinal absorption of glucose, and improving insulin sensitivity.
- It is preferred as initial therapy because it effectively lowers blood glucose without causing weight gain or hypoglycemia, has cardiovascular benefits, and is inexpensive.
- Patients should be aware of potential side effects including diarrhea, nausea, and abdominal discomfort, which often improve over time.
- Metformin should be temporarily discontinued before procedures requiring contrast dye and in cases of acute illness with dehydration risk.
- Kidney function should be monitored regularly, as the medication is contraindicated in patients with significantly impaired renal function (eGFR <30 mL/min) 1.
Patient-Centered Approach
A patient-centered approach should be used to guide the choice of pharmacologic agents, considering factors such as efficacy, hypoglycemia risk, effect on weight, side effects, cost, and patient preferences 1.
Additional Considerations
Long-term use of metformin may be associated with biochemical vitamin B12 deficiency, and periodic measurement of vitamin B12 levels should be considered in metformin-treated patients, especially in those with anemia or peripheral neuropathy 1. In patients with type 2 diabetes who have established atherosclerotic cardiovascular disease, sodium–glucose cotransporter 2 inhibitors or glucagon-like peptide 1 receptor agonists with demonstrated cardiovascular disease benefit are recommended as part of the antihyperglycemic regimen 1.
From the FDA Drug Label
Metformin hydrochloride tablets are used with diet and exercise to help control high blood sugar (hyperglycemia) in adults with type 2 diabetes.
The recommended first-line treatment for type 2 diabetes using Metformin is Metformin hydrochloride tablets in combination with diet and exercise to help control high blood sugar (hyperglycemia) in adults with type 2 diabetes 2.
- Key points:
- Metformin hydrochloride tablets are used to help control high blood sugar.
- They are used in combination with diet and exercise.
- They are for adults with type 2 diabetes.
- Metformin hydrochloride tablets are not for people with type 1 diabetes or diabetic ketoacidosis.
From the Research
Metformin as First-Line Treatment for Type 2 Diabetes
- Metformin is widely recommended as the first-line treatment for type 2 diabetes due to its efficacy in lowering blood glucose levels without increasing the risk of hypoglycaemia or weight gain 3, 4.
- The UK Prospective Diabetes Study (UKPDS) demonstrated a substantial beneficial effect of metformin therapy on cardiovascular disease (CVD) outcomes, with a 36% relative risk reduction in all cause mortality and a 39% relative risk reduction in myocardial infarction 3.
- Metformin acts by enhancing insulin sensitivity, inducing greater peripheral uptake of glucose, and decreasing hepatic glucose output, making it an effective treatment for type 2 diabetes 3, 4.
Efficacy and Safety of Metformin
- Metformin has been shown to lower fasting plasma glucose levels by approximately 1.5 mmol/l, and HbA1c levels by around 1.5% when used as monotherapy 3, 5.
- The most common side effects of metformin are gastrointestinal, and it is usually well tolerated 3, 4.
- Metformin has a low risk of lactic acidosis, with less than one case per 100,000 treated patients 3.
- The harm-benefit balance of metformin monotherapy remains favourable in most patients with type 2 diabetes when dietary measures alone are not sufficient 6.
Comparison with Other Treatments
- Metformin is considered the first-line glucose-lowering drug for patients with type 2 diabetes, with other treatments such as sulphonylureas, insulin, and gliptins having a less favourable harm-benefit balance 7.
- The combination of metformin with other diabetes medications can be effective in achieving glycaemic control, but the choice of treatment should be based on individual patient needs and adverse effect profiles 7, 4.