By Bruce Sylvester
SAN FRANCISCO -- June 9, 2008 -- Patients with type 2 diabetes treated with sitagliptin and metformin have a significantly lower risk of experiencing a confirmed symptomatic hypoglycaemic event (P = .001) compared with patients treated with a combination of glipizide and metformin, researchers reported here at the American Diabetes Association (ADA) 68th Scientific Sessions.
The benefit of sitagliptin was especially marked in patients aged 65 years or more, the researchers said.
"The risk of having documented, symptomatic hypoglycaemic events was substantially lower with sitagliptin," noted investigator Karl J. Krobot MD, PhD, MPH, Merck Sharp & Dohme Ltd., Haar, Germany, in a presentation on June 8.
The research by Dr. Krobot and colleagues was a subanalysis of a 52-week, randomised, double-blind, active-controlled study in which treatment with sitagliptin 100 mg once-daily or glipizide up to 20 mg daily (mean daily dose, 10 mg) was added to ongoing metformin therapy (>1,500 mg daily).
Combination treatment provided similar improvement in haemoglobin (Hb) A1C levels and blood glucose (0.7% in both groups).
All study subjects had been diagnosed with type 2 diabetes and had inadequate glycaemic control (Hb A1C, 6.5% to 10%) at baseline.
The original study demonstrated that fewer patients experienced hypoglycaemia (all reported cases) with sitagliptin compared with glipizide (5%, n = 588 vs 32%, n = 584).
The authors noted that "the purpose of the present prespecified analysis was to evaluate the [Hb] A1C-adjusted risk of a hypoglycaemic event on a given day."
The primary endpoint of the new analysis was patient-reported and physician-confirmed symptomatic hypoglycaemic events with documented fingerstick glucose measurements of 70 mg/dL (3.9 mmol/L) or less.
The investigators used standard statistical tools to assess comparative risk for each treatment, most recent Hb A1C value prior to the event, time from randomisation to the event, gender, age group (<65 years or >=65 years), and interaction terms (P < .02 considered significant).
The researchers evaluated 37 sitagliptin-related and 492 glipizide-related primary events of hypoglycaemia among intent-to-treat subjects.
They reported that sitagliptin subjects achieved a 93% lower risk of having a symptomatic hypoglycaemic event on a given day (random effects hazard ratio [HR], 0.07; 95% confidence interval [CI], 0.04-0.11; P = .001).
Recent Hb A1C level, time from randomisation to event, and gender all significantly affected the risk of hypoglycaemia in both treatment groups (P <= .001).
The researchers found a significant interaction for treatment by age group (P = .11), with an 11-fold lower risk for sitagliptin versus glipizide in the group aged <65 years (HR, 0.09; 95% CI, 0.06-0.15; P < .001) and a 29-fold lower risk in the group aged >=65 years (HR, 0.03; 95% CI, 0.01-0.11; P < .001).
The authors concluded that the risk of having documented, symptomatic hypoglycaemic events was substantially lower with sitagliptin compared with glipizide and was especially marked in older patients.
[Presentation title: Lower Risk of Hypoglycemia With Sitagliptin Compared to Glipizide When Added to Ongoing Metformin Therapy: An Analysis Based on A1C-Adjusted Event Rates. Abstract #: 2195]
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