# A nurse is teaching a 52-year-old patient newly diagnosed with type 2 diabetes mellitus about metformin therapy. Which statements by the nurse are correct? Select all that apply.

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> subject: NCLEX-RN  
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## Question

A nurse is teaching a 52-year-old patient newly diagnosed with type 2 diabetes mellitus about metformin therapy. Which statements by the nurse are correct? Select all that apply.

1

Take metformin with meals to reduce gastrointestinal side effects such as nausea and diarrhea.

2

Alcohol use should be minimized because it increases the risk of lactic acidosis.

3

Monitor for symptoms of lactic acidosis including muscle pain, weakness, and difficulty breathing.

4

Metformin must be held 48 hours before and after receiving iodinated contrast media.

5

Metformin monotherapy often leads to hypoglycemia, so blood glucose should be checked before each dose.

## Explanation

Metformin (a biguanide) decreases hepatic glucose production and improves insulin sensitivity without stimulating insulin secretion. Correct teaching includes: taking with meals (choice 1) to reduce GI effects; holding before contrast media (choice 4) due to risk of contrast-induced nephropathy causing metformin accumulation and lactic acidosis; limiting alcohol (choice 2) which independently raises lactic acidosis risk; and monitoring for lactic acidosis symptoms (choice 3). Choice 5 is incorrect — metformin as monotherapy does NOT cause hypoglycemia because it does not increase insulin secretion.

## In-depth explanation

Key metformin nursing education points: (1) Take with or immediately after meals to blunt GI side effects; GI symptoms are the most common reason patients stop the drug. (2) Hold for 48 h around iodinated contrast — creatinine rise from contrast nephropathy impairs renal clearance of metformin, raising plasma levels and lactic acidosis risk. (3) Lactic acidosis is rare (<1/10,000 patient-years) but fatal if missed; risk factors include renal impairment (eGFR <30), hepatic disease, heavy alcohol use, dehydration. (4) Metformin monotherapy does not cause hypoglycemia — it works by reducing hepatic glucose output, not by stimulating insulin. This is a key differentiator from sulfonylureas.

## Clinical scenario

A **52-year-old patient** has been newly diagnosed with **type 2 diabetes mellitus** and prescribed **metformin**. The nurse is providing medication education prior to discharge.

## Key concepts

- **Lactic Acidosis** — A rare but serious complication of metformin therapy in which lactate accumulates in the blood (pH <7.35, lactate >5 mmol/L). Risk factors: renal impairment (eGFR <30), liver disease, heavy alcohol use, dehydration. Symptoms: muscle pain, weakness, abdominal discomfort, rapid breathing.
- **Contrast-Induced Nephropathy** — Acute kidney injury following administration of iodinated contrast media. Reduced renal function impairs metformin clearance, elevating plasma metformin levels and lactic acidosis risk. Metformin should be held 48 h before and after contrast in patients at risk.
- **Biguanide** — Drug class that includes metformin. Mechanism: inhibits mitochondrial complex I in hepatocytes, reducing hepatic glucose production (gluconeogenesis) and increasing peripheral insulin sensitivity. Does not stimulate insulin secretion — therefore no risk of hypoglycemia as monotherapy.

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