What is the recommended starting dose of Gliclazide (sulfonylurea) for a patient with type 2 diabetes?

Gliclazide Starting Dose for Type 2 Diabetes

The recommended starting dose of gliclazide for a patient with type 2 diabetes is 40 mg once daily (standard formulation) or 30 mg once daily (modified release formulation), taken with breakfast. 1, 2

Standard Dosing Recommendations

Initial Dosing by Formulation

• Standard gliclazide: Start at 40 mg once or twice daily, with a maximum dose of 320 mg/day divided into two doses 1
• Gliclazide modified release (MR): Start at 30 mg once daily at breakfast, with titration up to 60-120 mg once daily as needed 1, 2

The modified release formulation provides effective 24-hour glycemic control with once-daily dosing, which improves compliance and maintains consistent plasma glucose reduction throughout the day and night 2

Dose Modifications for Renal Impairment

Conservative Dosing Required

• eGFR 30-50 mL/min/1.73 m²: Start conservatively at 2.5 mg daily (using glipizide as reference for sulfonylurea class dosing in renal impairment) and titrate slowly due to increased hypoglycemia risk 3
• eGFR <30 mL/min/1.73 m²: Consider alternative agents entirely, as sulfonylureas carry substantial hypoglycemia risk in advanced kidney disease 3

While gliclazide has demonstrated safety in patients with impaired renal function in clinical trials, the incidence of hypoglycemia remains low but present (4.8 episodes per 100 patient-years), necessitating cautious dosing 1

Special Population Considerations

Elderly Patients

• Use the same starting doses as above, but monitor closely for hypoglycemia
• The safety profile in elderly patients is favorable, with no increase in severe hypoglycemic events compared to younger patients 1

Patients with Well-Controlled HbA1c

• If baseline HbA1c is already well-controlled or if there is a history of frequent hypoglycemic events, consider starting at lower doses or choosing alternative agents with lower hypoglycemia risk 4

Important Clinical Caveats

Hypoglycemia Risk

• Gliclazide carries a lower hypoglycemia risk compared to glyburide, but symptoms suggestive of hypoglycemia still occur 1, 5
• Even at low doses (20 mg/day), gliclazide produces more hypoglycemic symptoms than rapid-acting secretagogues like nateglinide, though it achieves modestly better glycemic control 5

Modern Treatment Context

• Gliclazide and other sulfonylureas are not preferred first-line agents in contemporary diabetes management, particularly in patients with established cardiovascular disease, heart failure, or chronic kidney disease 3
• SGLT2 inhibitors and GLP-1 receptor agonists should be prioritized in these populations due to proven cardiovascular and renal benefits 3, 4

Timing and Administration

• Administer gliclazide at breakfast to optimize 24-hour glycemic coverage and minimize nocturnal hypoglycemia risk 2
• Peak serum levels occur approximately 2 hours after administration, with steady-state achieved within 2 days of consecutive dosing 6