Considerations for Using Hydroxyurea and Insulin Together
When using hydroxyurea and insulin together in patients, careful monitoring of glucose levels is essential as hydroxyurea may falsely elevate sensor glucose readings from certain continuous glucose monitoring (CGM) systems, potentially leading to inappropriate insulin dosing and hypoglycemia. 1
Hydroxyurea and Glucose Monitoring Interference
Hydroxyurea can interfere with laboratory tests used for determining urea, uric acid, and lactic acid, producing falsely elevated results in patients receiving this medication 1
Specifically with CGM systems, hydroxyurea may falsely elevate sensor glucose results, which is particularly concerning if these readings are used to determine insulin dosing 1
The Dexcom CGM system shows significant inaccuracy after hydroxyurea administration with a mean absolute relative difference (MARD) of 59.5% compared to point-of-care blood glucose testing 2
In contrast, the Libre CGM system appears to maintain accuracy after hydroxyurea administration with a MARD of only 14.8%, making it a potentially better option for patients on both medications 2
Clinical Management Recommendations
For patients requiring both hydroxyurea and insulin therapy, consult with the CGM prescriber about alternative glucose monitoring methods 1
Consider using fingerstick blood glucose measurements to verify CGM readings, especially in the hours following hydroxyurea administration 2
When using insulin with hydroxyurea, be aware that lower insulin doses may be required with decreased renal function; titrate according to clinical response 3
No specific medication interactions between hydroxyurea and insulin are listed in current guidelines, but careful monitoring is warranted due to the potential for laboratory test interference 1
Insulin Administration Considerations
No other medication or diluent should be mixed with any insulin product unless specifically approved by the prescribing physician 3
Insulin has a high risk of hypoglycemia, which requires careful monitoring, especially when combined with medications that may affect glucose readings 3
For patients with diabetes who also require hydroxyurea (such as those with sickle cell disease), insulin therapy should be individualized based on glucose monitoring that accounts for potential hydroxyurea interference 1, 2
Specific Patient Populations
In patients with sickle cell disease (a common indication for hydroxyurea), monitor for improvements in clinical outcomes such as increased hemoglobin levels and reduced vaso-occlusive crises while maintaining appropriate glycemic control 4, 5
For patients with both diabetes and sickle cell disease, hydroxyurea has been shown to be generally safe with mostly mild, reversible side effects such as neutropenia and thrombocytopenia 4
Be particularly vigilant about glucose monitoring in pediatric patients receiving both medications, as studies have shown significant differences in CGM accuracy after hydroxyurea administration 2
Monitoring and Follow-up
Regular monitoring of complete blood counts is recommended for patients on hydroxyurea, as it can cause bone marrow suppression 1
When initiating hydroxyurea in a patient already on insulin therapy, more frequent blood glucose monitoring may be necessary to ensure appropriate insulin dosing 2
If a patient experiences unexpected glucose fluctuations after starting hydroxyurea, consider the possibility of CGM interference and verify with alternative glucose measurement methods 2
For patients requiring both medications long-term, establish a consistent monitoring protocol that accounts for the potential interference of hydroxyurea with glucose measurements 1, 2