Discontinue Glimepiride First When Starting Mounjaro
When initiating tirzepatide (Mounjaro), you should discontinue glimepiride (the sulfonylurea) first, before stopping either the DPP-4 inhibitor (gliptin) or SGLT2 inhibitor.
Rationale for This Recommendation
Why Stop Glimepiride First
The primary concern when starting tirzepatide is hypoglycemia risk, particularly when combined with insulin secretagogues like sulfonylureas 1. The FDA label for Mounjaro explicitly warns that patients receiving tirzepatide with insulin secretagogues (e.g., sulfonylurea) have an increased risk of hypoglycemia, including severe hypoglycemia, and recommends that "the risk of hypoglycemia may be lowered by a reduction in the dose of sulfonylurea" 1.
The 2020 ACC Expert Consensus specifically advises to "wean or stop sulfonylurea" when starting GLP-1 receptor agonists (and by extension, dual GIP/GLP-1 agonists like tirzepatide) if HbA1c is well-controlled at baseline 2. This guidance applies directly to tirzepatide given its similar mechanism and even more potent glucose-lowering effects 3.
Why Keep the DPP-4 Inhibitor Temporarily
While DPP-4 inhibitors should eventually be discontinued when starting tirzepatide (as they work on overlapping pathways), they pose no hypoglycemia risk when used alone 4. The 2025 ADA Standards note that DPP-4 inhibitors have intermediate efficacy with no hypoglycemia risk and neutral effects on weight 4. You can safely continue the DPP-4 inhibitor briefly during the tirzepatide titration phase, then discontinue it once tirzepatide reaches therapeutic doses.
Why Keep the SGLT2 Inhibitor
SGLT2 inhibitors should be continued indefinitely when starting tirzepatide, as they provide complementary cardiorenal benefits that tirzepatide does not replicate 5, 6. The 2020 KDIGO guidelines explicitly state that SGLT2 inhibitors can be added to other antihyperglycemic medications, and if additional glucose-lowering may increase hypoglycemia risk, "it may be necessary to stop or reduce the dose of an antihyperglycemic drug other than metformin" to facilitate SGLT2 inhibitor addition 5. This same principle applies when adding tirzepatide—you preserve the SGLT2 inhibitor for its proven cardiovascular and kidney protection 6, 4.
Practical Implementation Algorithm
Step 1 (Day 1):
- Discontinue glimepiride completely
- Continue DPP-4 inhibitor temporarily
- Continue SGLT2 inhibitor indefinitely
- Start tirzepatide at 2.5 mg weekly
Step 2 (Weeks 1-12):
- Titrate tirzepatide by 2.5 mg every 4 weeks toward target dose
- Monitor for hypoglycemia (though risk is low without sulfonylurea)
- Continue both DPP-4 inhibitor and SGLT2 inhibitor
Step 3 (After reaching therapeutic tirzepatide dose):
- Discontinue DPP-4 inhibitor (overlapping mechanism with tirzepatide)
- Continue SGLT2 inhibitor permanently for cardiorenal protection
Important Caveats
Hypoglycemia monitoring: Even after stopping glimepiride, educate patients on hypoglycemia symptoms during the first 4 weeks, though the absolute risk is low with tirzepatide alone 2, 1.
SGLT2 inhibitor continuation: The SGLT2 inhibitor provides benefits independent of glucose control—including heart failure reduction, kidney disease slowing, and cardiovascular event reduction—that tirzepatide does not provide 5, 6. These are separate therapeutic targets that should not be abandoned.
DPP-4 inhibitor timing: The 2020 ACC guidelines state to "discontinue DPP-4 inhibitor before starting" GLP-1 receptor agonists 2. However, given the lack of hypoglycemia risk and the gradual titration of tirzepatide, a brief overlap during dose escalation is clinically reasonable and safer than maintaining the sulfonylurea.