From the Guidelines
Bactrim (sulfamethoxazole-trimethoprim) can significantly affect blood glucose levels, particularly by increasing the risk of hypoglycemia in patients taking sulfonylureas, and thus requires careful monitoring and potential adjustment of diabetes medications. This is because Bactrim interacts with sulfonylureas, enhancing their effect and leading to an increased risk of hypoglycemia, as noted in the most recent guidelines 1. Patients with diabetes, especially those on sulfonylureas, should be aware of this potential interaction and monitor their blood glucose levels more frequently when starting Bactrim therapy.
The mechanism behind this interaction involves the competition for protein binding sites between Bactrim and sulfonylureas, which can affect the metabolism of glucose-regulating medications, potentially leading to hypoglycemia 1. Elderly patients and those with kidney impairment are at a higher risk for these blood glucose fluctuations due to decreased drug clearance and altered drug metabolism.
Key considerations for managing patients on Bactrim and sulfonylureas include:
- Monitoring blood glucose levels frequently
- Being aware of the signs and symptoms of hypoglycemia
- Potential temporary adjustment or discontinuation of sulfonylureas during Bactrim therapy, as suggested by recent standards of care 1
- Close communication with healthcare providers to manage any changes in blood glucose levels promptly.
Given the potential for significant interactions and the importance of maintaining tight blood glucose control to prevent morbidity and mortality, it is crucial for healthcare providers to be vigilant about this interaction and to take proactive steps to mitigate its effects, particularly in vulnerable populations such as the elderly and those with renal impairment, based on the latest evidence 1.
From the FDA Drug Label
Like other sulfonamide-containing drugs, sulfamethoxazole and trimethoprim potentiates the effect of oral hypoglycemic that are metabolized by CYP2C8 (e.g., pioglitazone, repaglinide, and rosiglitazone) or CYP2C9 (e.g., glipizide and glyburide) or eliminated renally via OCT2 (e.g., metformin). Additional monitoring of blood glucose may be warranted. Cases of hypoglycemia in non-diabetic patients treated with sulfamethoxazole and trimethoprim are seen rarely, usually occurring after a few days of therapy Patients with renal dysfunction, liver disease, malnutrition or those receiving high doses of sulfamethoxazole and trimethoprim are particularly at risk.
Bactrim (Trimethoprim/Sulfamethoxazole) can affect blood glucose levels by potentiating the effect of oral hypoglycemics and causing hypoglycemia in rare cases, especially in patients with certain underlying conditions.
- Patients with renal dysfunction, liver disease, malnutrition, or those receiving high doses of sulfamethoxazole and trimethoprim are at increased risk.
- Additional monitoring of blood glucose may be warranted, especially when co-administering oral hypoglycemics with sulfamethoxazole and trimethoprim 2.
From the Research
Bactrim (Trimethoprim/Sulfamethoxazole) and Blood Glucose Levels
- Bactrim (Trimethoprim/Sulfamethoxazole) has been associated with hypoglycemia in some cases, particularly in patients with renal insufficiency 3, 4.
- The mechanism of hypoglycemia is thought to be due to a sulfonylurea-like effect of sulfamethoxazole, which can increase serum insulin levels 3.
- Trimethoprim may also inhibit the metabolism of certain oral hypoglycemic agents, such as glipizide, increasing the risk of hypoglycemia 5.
- However, not all studies have found a significant effect of trimethoprim-sulfamethoxazole on blood glucose levels in diabetic patients 6.
- Patients with renal dysfunction may be at increased risk of hypoglycemia due to accumulation of trimethoprim and sulfamethoxazole 7, 3.
Risk Factors for Hypoglycemia
- Renal insufficiency is a common predisposing risk factor for hypoglycemia associated with trimethoprim-sulfamethoxazole use 3, 4.
- Age and history of alcohol abuse may also increase the risk of hypoglycemia in patients taking trimethoprim-sulfamethoxazole 5.
- Concomitant use of oral hypoglycemic agents, such as repaglinide, may increase the risk of hypoglycemia due to interactions with trimethoprim-sulfamethoxazole 7.