Can metoprolol (beta-blocker) cause hypoglycemia?

Metoprolol and Hypoglycemia Risk

Beta-1 selective agents like metoprolol are less likely to cause hypoglycemia than non-selective beta-blockers, but they can still mask hypoglycemic symptoms in diabetic patients and may impair glucose recovery from hypoglycemia. 1, 2

Mechanism and Risk

• Beta-blockers, including metoprolol, can mask tachycardia occurring with hypoglycemia, though other manifestations such as dizziness and sweating may not be significantly affected 2
• Evidence indicates that beta-blockers in diabetic patients alter counter-regulatory responses to hypoglycemia with decreased tremor and palpitations but increased sweating 1
• Prolonged hypoglycemia has been described with non-cardio-selective beta-blockade (propranolol), but is less common with beta-1-selective agents like metoprolol 1

Comparative Risk Between Beta-Blockers

• Elderly diabetic patients on insulin experienced an increased risk of serious hypoglycemia with non-selective beta-blockade (RR 2.16; 95% CI 1.15–4.02) but not with beta-1-selective drugs like metoprolol (RR 0.86; 95% CI 0.36–1.33) 1
• However, research has shown that both metoprolol and propranolol can impair recovery from insulin-induced hypoglycemia in insulin-dependent diabetes mellitus 3
• At a dose of 100 mg, oral metoprolol was found to be no safer than oral propranolol with respect to recovery from hypoglycemia in patients with insulin-dependent diabetes mellitus 3

Clinical Considerations

• Patients with diabetes who require beta-blockers should preferentially receive cardioselective agents like metoprolol rather than non-selective beta-blockers 1, 4
• The FDA label for metoprolol specifically warns that beta-blockers may mask tachycardia occurring with hypoglycemia, though other manifestations such as dizziness and sweating may not be significantly affected 2
• In patients with heart failure and diabetes, carvedilol might have more favorable effects on glycemic control than metoprolol succinate and bisoprolol 1

Monitoring and Precautions

• When prescribing metoprolol to diabetic patients, healthcare providers should monitor blood glucose levels regularly, particularly during the initial months of therapy 5
• Patients should be educated about the potential masking of hypoglycemic symptoms and the need for more vigilant blood glucose monitoring 6, 2
• Metoprolol should be administered with caution in patients at risk for hypoglycemia, and patients should be instructed to report any unusual symptoms 2

Special Populations

• In children receiving propranolol (another beta-blocker), administering the medication with feeds and holding doses during times of diminished oral intake or vomiting is recommended to reduce hypoglycemia risk 1
• This principle can be applied to adult patients taking metoprolol who are at high risk for hypoglycemia 1

While metoprolol has a better safety profile regarding hypoglycemia than non-selective beta-blockers, clinicians should remain vigilant about the potential for masked hypoglycemic symptoms and impaired recovery from hypoglycemia, especially in insulin-dependent diabetic patients 1, 2, 3.