New drugs reduce blood sugar.

Two experimental drugs can lower blood sugar significantly in people with type 2 diabetes, research shows. If approved by the Food and Drug Administration, the drugs could represent a new class of diabetes medication.

Both compounds inhibit an enzyme called dipeptidyl peptidase 4 (DPP-4), which usually controls the body's production of a hormone, called GLP1. Cells lining the intestines normally release GLP1 in response to ingested sugars, and the hormone then alerts cells in the pancreas to release insulin for sugar regulation (SN: 8/16/03, p. 104).

But GLP1 lasts only minutes in the body because DPP-4 breaks it down. Researchers have hypothesized that suppressing the enzyme would make more GLP1 available to the pancreas cells to stabilize insulin production.

Two groups now report that DPP-4 inhibitors significantly lower blood sugar compared with placebos. The effects showed up when the inhibitors were taken alone or in combination with other diabetes drugs.

One of the new drugs, sitagliptin, is made by Merck Research Laboratories of Rahway, N.J. The other, called vildagliptin, is made by Basel, Switzerland-based Novartis.

Compared with a placebo, neither drug caused more occurrences of a severe drop in blood sugar.

"DPP-4 inhibition is a mechanism by which we can enhance the body's own glucose regulation" says Merck scientist Peter Stein.

The DPP-4 inhibitors show great promise, agrees John B. Buse of the University of North Carolina School of Medicine in Chapel Hill. But even though they appear safe in these studies, the drugs' full impact may not be apparent until they're taken by thousands of people for many years. "There are many [compounds in the body] degraded by DPP-4," he notes, and inhibiting the enzyme could increase those compounds' concentrations, with yet-unknown effects.--N.S.