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.
Select All That Apply
Choose your responses, then check the answer.
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.
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.
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.
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.