Diabetes Care, Vol 17, Issue 12 1460-1464, Copyright © 1994 by American Diabetes Association
Comparative efficacy of a once-daily controlled-release formulation of glipizide and immediate-release glipizide in patients with NIDDM
M Berelowitz, C Fischette, W Cefalu, DS Schade, T Sutfin and IA Kourides
Division of Endocrinology and Metabolism, SUNY at Stony Brook 11794.
OBJECTIVE--To compare the efficacy and safety of controlled-release
glipizide (glipizide-GITS [gastrointestinal therapeutic system]) and
immediate-release glipizide in patients with non-insulin-dependent diabetes
mellitus (NIDDM). RESEARCH DESIGN AND METHODS--In a multicenter,
open-label, randomized, two-way crossover study, 132 patients with NIDDM
received daily doses of 5, 20, or 40 mg of either glipizide-GITS or
immediate-release glipizide for 8 weeks followed by 8 weeks of the
alternate formulation. Plasma glucose, serum insulin, C-peptide, and plasma
glipizide levels were measured at fasting and post-Sustacal challenge at
the end of 1 and 8 weeks of each treatment phase. HbA1c was measured at the
end of weeks 7 and 8 of each treatment phase. RESULTS--Both formulations of
glipizide yielded similar mean HbA1c values. However, mean fasting plasma
glucose (FPG) levels were significantly lower with glipizide-GITS treatment
than with immediate-release glipizide at the end of week 1 (11.0 vs. 11.6
mmol/l; P < 0.01) and at the end of the 8-week treatment phase (10.9 vs.
11.7 mmol/l; P < 0.001). Fasting insulin and C-peptide levels were lower
after 5 mg glipizide-GITS vs. immediate-release glipizide. Glucose
responses to Sustacal were similar after both formulations of glipizide;
however, serum insulin (P < 0.01) and C-peptide responses (P < 0.05)
were lower with glipizide-GITS than with immediate-release glipizide
treatment at the end of the 8-week treatment phase. Mean plasma glipizide
concentrations were stable by the end of week 1, and the concentrations
increased proportionately with dose. Once-daily Glipizide-GITS provided
effective mean glipizide concentrations (> 50 ng/ml) 24 h after dosing,
even at the lowest (5 mg) dose level. Both formulations were well
tolerated. CONCLUSIONS--Glipizide-GITS was significantly more effective
than immediate-release glipizide in reducing FPG levels. Both formulations
reduced postprandial plasma glucose levels equally; however, glipizide-GITS
exerted its control in the presence of lower plasma glipizide
concentrations in addition to significantly lower insulin and C-peptide
levels. This suggests that glipizide-GITS improves insulin sensitivity.