Initial Dosing of Glipizide for Patients with Type 2 Diabetes
The recommended initial dose of glipizide for most patients is 2.5 mg once daily, taken approximately 30 minutes before breakfast. 1, 2
Dosing Recommendations Based on Patient Characteristics
- For standard adult patients, start with 5 mg taken before breakfast 1
- For elderly patients, debilitated patients, or those with liver disease, start with 2.5 mg 1
- For patients with renal impairment (eGFR 30-45 mL/min/1.73m²), initiate conservatively at 2.5 mg daily 2
- For patients with severe renal impairment (eGFR <30 mL/min/1.73m²), use with caution and start with 2.5 mg daily 2
Timing of Administration
- Administer glipizide approximately 30 minutes before breakfast to achieve the greatest reduction in postprandial hyperglycemia 1, 3
- Taking glipizide 30 minutes before meals allows the drug to reach peak concentration before meal-induced hyperglycemia, optimizing its hypoglycemic effect 3, 4
- When taken with or after meals, absorption is delayed and peak concentration is smaller, resulting in less effective control of postprandial hyperglycemia 3, 4
Dose Titration Guidelines
- Allow several days between dose adjustments to evaluate response 1
- Make dose adjustments in increments of 2.5-5 mg based on blood glucose response 1
- If response to a single dose is not satisfactory, dividing the daily dose may prove more effective 1
- Maximum recommended once-daily dose is 15 mg 1
- Total daily doses above 15 mg should be divided and given before meals 1
- Maximum total daily dose should not exceed 40 mg 1
Special Considerations
- For patients with chronic kidney disease (CKD), conservative initial dosing is recommended to avoid hypoglycemia 2
- In patients with CKD stage 3b-5 (eGFR <45 mL/min/1.73m²), initiate conservatively (e.g., 2.5 mg once daily) and titrate slowly to avoid hypoglycemia 2
- For patients previously on insulin, if daily insulin requirement is ≤20 units, insulin may be discontinued and glipizide started at usual dosages 1
- For patients on insulin >20 units daily, reduce insulin by 50% when starting glipizide 1
- Patients switching from other sulfonylureas should be observed carefully for 1-2 weeks for hypoglycemia, especially when transferring from longer-acting agents like chlorpropamide 1
Monitoring Recommendations
- Monitor blood glucose regularly to determine the minimum effective dose 1
- For patients transitioning from insulin, test urine for sugar and ketone bodies at least three times daily during the transition period 1
- Monitor for signs of hypoglycemia, especially in elderly, debilitated, or malnourished patients and those with impaired renal or hepatic function 1, 2
- Consider hospitalization during transition for patients previously on >40 units of insulin daily 1
Pharmacokinetic Considerations
- Glipizide has a rapid onset of action but shorter duration compared to some other sulfonylureas 5, 6
- The drug is completely absorbed after oral administration but absorption is delayed by food 5, 7
- Terminal elimination half-life ranges from 2-7 hours 7
- Despite rapid elimination, once-daily dosing is often sufficient due to possible enterohepatic recirculation in response to meals 6
Starting with the lower 2.5 mg dose is particularly important for vulnerable populations to minimize the risk of hypoglycemia while still providing effective glycemic control.