The Oil Price Information Service has warned that supplies of diesel fuel in the Midwest are low and price increases could follow. OPIS announced on Aug. 29 that current supplies of diesel fuel are below three million barrels in the Midwest, more than 20 percent behind last year's figures. "Expressed in terms of days' supply the numbers are more scary. Current diesel supply is estimated to be 26.3 days," OPIS said. Demand for diesel in the region has remained steady, even as inventories have continued to fall, OPIS said. The group believes that it may be too late to avoid a price hike by rebuilding fuel supplies.