Merck & Co has unveiled data showing that its oral, once-daily medicine for type 2 diabetes, Januvia (sitagliptin phosphate), drug was at least as effective as the widely-used sulfonylurea glipizide in patients who had failed to respond to prior treatment with metformin.

After one year’s treatment, 63% of patients treated with Januvia had a haemoglobin A1c level of less than 7%, compared to 59% of the glipizide group. HbA1c is a widely-used measure of glucose control over time, and 7% or less is the target level set by the American Diabetes Association in its treatment guidelines.

Moreover, patients on Januvia experienced significant weight loss after a year, while those on glipizide gained weight over the course of the study. Weight gain is a common side effect of diabetes treatment and can reduce compliance with therapy, as well as elevating patients’ risk of cardiovascular disease.

Earlier, Merck reported at the ADA that Januvia significantly reduced blood glucose levels when used as monotherapy or as an add-on treatment to two commonly used therapies, metformin or GlaxoSmithKline’s Avandia (rosiglitazone). It also reported data reinforcing the hypothesis that Januvia improves the function of pancreatic beta cells that synthesise and release insulin.

If approved, Januvia would be the first in a new class of oral drugs - the dipeptidyl peptidase-4 inhibitors - that enhance the body's own ability to lower blood sugar when it is elevated.

Meanwhile, another company aiming to bring a DDP-4 inhibitor to market, Novartis, presented data at the ADA on its Galvus (vildagliptin) in combination with Eli Lilly/Takeda’s Actos (pioglitazone), revealing that the drug was more effective than Actos alone in reducing blood glucose levels.

65% of patients on the combination achieved HbA1c levels of less than 7%, compared to 42% of those on Actos monotherapy. The results showed no significant additional weight gain and less oedema with the combination compared to pioglitazone alone.

Meanwhile, a separate head-to-head comparison with Avandia showed that Galvus was as effective at reducing blood glucose levels. Novartis drug was also able to achieve weight loss in this obese patient group, while Avandia was associated with weight gain.

Novartis said it was initiating a new clinical trials programme, dubbed GLORIOUS, that will look at the impact of Galvus on progression of type 2 diabetes and patient outcomes.

Galvus was accepted for US regulatory review earlier this year, about a month later than Januvia, and regulatory filings in the EU are planned later in 2006.

The market for DPP-4 inhibitors could be in the region of $3 billion in the USA alone, according to Morgan Stanley, assuming they win a half share of the market for sulfonylureas. Both GlaxoSmithKline and Bristol-Myers Squibb are also working on drugs in this class.