Does Spironolactone Increase Blood Sugar?
Spironolactone can cause hyperglycemia and may slightly increase blood sugar levels, as explicitly stated in the FDA drug label, though this effect is generally mild and often clinically insignificant for most patients. 1
Mechanism and Evidence
The FDA drug label for spironolactone specifically lists hyperglycemia among its potential metabolic abnormalities 1. This is supported by a meta-analysis of randomized controlled trials that found spironolactone increased hemoglobin A1c by 0.16% (95% CI: 0.02 to 0.30), though it had no clear effect on fasting glucose, insulin resistance, or insulin levels 2.
The European Society of Cardiology working group on cardiovascular pharmacotherapy also acknowledges that spironolactone can cause metabolic disturbances, including hyperglycemia, particularly in elderly patients 3.
Clinical Significance and Risk Factors
The effect of spironolactone on glucose metabolism appears to be:
- Mild: The increase in HbA1c (0.16%) is modest 2
- Possibly transient: Some older research suggests the effect may be temporary 4
- Less significant than thiazide diuretics: Unlike thiazides, spironolactone's effect on glucose metabolism is generally less pronounced 5
Risk factors for developing hyperglycemia with spironolactone include:
- Advanced age
- Pre-existing diabetes or impaired glucose tolerance
- Higher doses (dose-dependent effect)
- Concomitant use of other medications that affect glucose metabolism
Monitoring Recommendations
For patients taking spironolactone:
- Monitor serum electrolytes, uric acid, and blood glucose periodically 1
- More frequent monitoring may be needed in:
- Elderly patients
- Patients with diabetes
- Patients with kidney disease
- Those taking other medications that affect glucose metabolism
Clinical Context
The hyperglycemic effect of spironolactone should be weighed against its benefits:
- In heart failure patients, a large cohort study found no increased risk of new-onset diabetes with spironolactone use (HR = 0.92; 95% CI = 0.72-1.18) 6
- For patients with acne, the American Academy of Dermatology guidelines do not specifically mention glucose monitoring as a requirement 3
- In patients with diabetes and kidney disease, the American Diabetes Association and KDIGO note that spironolactone can cause hyperkalemia but do not specifically highlight concerns about worsening glycemic control 3
Practical Considerations
- For patients without diabetes: Routine glucose monitoring is generally not required unless other risk factors are present
- For patients with diabetes or pre-diabetes: Monitor glucose more closely when initiating or adjusting spironolactone dosage
- For elderly patients: Consider more careful monitoring of glucose levels, especially when using higher doses
In conclusion, while spironolactone can cause hyperglycemia, this effect is typically mild and should not preclude its use when clinically indicated, though appropriate monitoring is recommended, particularly in high-risk populations.