Metformin

 Metformin – Full Introduction

Metformin is a widely prescribed oral antihyperglycemic agent used in the management of type 2 diabetes mellitus (T2DM). It belongs to the biguanide class and is considered the first-line therapy for T2DM due to its efficacy, safety, and cardiovascular benefits.

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Drug Class

• Biguanide

• Oral antidiabetic agent

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Mechanism of Action

Metformin primarily lowers blood glucose levels through multiple mechanisms:

1. Decreases hepatic gluconeogenesis – reduces glucose production in the liver

2. Improves insulin sensitivity – enhances peripheral glucose uptake (mainly in muscle)

3. Delays intestinal glucose absorption – minor effect

4. Does not stimulate insulin secretion, so risk of hypoglycemia is low when used alone

Additionally, metformin may have favorable effects on lipid profiles and cardiovascular risk.

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Therapeutic Uses

• Type 2 diabetes mellitus (first-line therapy)

• Polycystic ovary syndrome (PCOS) – off-label, for insulin resistance

• Obesity-related insulin resistance – adjunct therapy

• Pre-diabetes – sometimes used to prevent progression to T2DM

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Benefits

• Effective at lowering fasting and postprandial blood glucose

• Weight neutral or modest weight loss

• Low risk of hypoglycemia as monotherapy

• Cardiovascular protective effects

• Inexpensive and widely available

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Common Side Effects

• Gastrointestinal upset (nausea, vomiting, diarrhea, abdominal discomfort) – most common

• Metallic taste in mouth

• Mild anorexia

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Serious but Rare Side Effects

• Lactic acidosis – rare but life-threatening, usually in patients with renal impairment, liver disease, or hypoxia

• Vitamin B12 deficiency (long-term use)

• Severe diarrhea or malabsorption

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Contraindications & Precautions

• Severe renal impairment (eGFR <30 mL/min/1.73 m²)

• Acute or chronic metabolic acidosis, including diabetic ketoacidosis

• Severe hepatic impairment

• Conditions predisposing to hypoxia (heart failure, respiratory failure)

• Avoid excessive alcohol intake

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Dosage & Administration

• Immediate-release: 500 mg once or twice daily, titrated up to 2000–2550 mg/day

• Extended-release: once daily, titrated to 2000 mg/day

• Taken with meals to reduce gastrointestinal side effects

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Conclusion

Metformin is a cornerstone drug in type 2 diabetes management due to its efficacy, safety, and additional cardiovascular and metabolic benefits. Regular monitoring of renal function, vitamin B12 levels, and signs of lactic acidosis is essential during long-term therapy.