Do geriatrics require dose titration for antidiabetic agents?

To evaluate the antidiabetic drug dosage differences between geriatric and nongeriatric diabetics with reference to duration of disease and creatinine clearance (Crcl).

Prospective study conducted for 6 months in a tertiary care hospital. Patients with type 2 diabetes mellitus were grouped into geriatric (age ≥60 years) and nongeriatric (age <60 years). Patients' demographic data, duration of diabetes, medication, and serum creatinine were recorded. Crcl was calculated using Cockcroft-Gault formula. Doses of sulfonylureas (SU) were converted into equivalent doses, taking glibenclamide as standard. Univariate analysis was done for comparison of drug doses between groups.

A total of 320 geriatric and 157 nongeriatric diabetics completed the study. The duration of diabetes and Crcl adjusted dose reduction of glibenclamide (mean dose: Geriatrics 7.2±0.4 mg, nongeriatrics 9.6±0.7 mg; P=0.01) and gliclazide (mean dose: Geriatrics 85.5±11.5 mg, nongeriatrics 115.3±32.7 mg; P=0.42) was 25%, glimepiride (mean dose: Geriatrics 1.62±0.13 mg, nongeriatrics 2.1±0.18 mg; P=0.06) was 22%. Glipizide did not require dose reduction. Mean converted equivalent dose of sulfonylurea monotherapy was significantly lower in geriatrics than nongeriatrics (3.2±0.5 vs 6.4±1.02 mg; P=0.01) and showed 50% dose reduction. Mean dose of metformin was lower in geriatrics (901±32.2 mg vs 946.7±45.8 mg; P=0.45) and showed 5% reduction in dosage. There was no difference in the mean drug doses of thiazolidinediones and insulin between the groups.

A substantial dose reduction of glibenclamide (25%), gliclazide (25%), glimepiride (22%), and metformin (5%) in geriatrics compared to nongeriatrics was observed. Smaller dosage formulations like 0.75 mg glibenclamide, 0.5 mg glimepiride, 20 mg gliclazide, and 250 mg metformin may be of value in geriatric diabetic practice.