With the price of diesel fuel soaring to new highs this month, something's gotta give. Eventually, people are going to start using less of it or the government is going to step in-either one could be a problem for energy companies, which have already made billions off the price surge.

The issue is coming to a head. Diesel prices were already flashing warning signs for the economy a month ago. Then things got much worse. Prices surged to record highs in Europe last week, and reached a new record in the U.S. on Tuesday of just over $6.52 a gallon, up almost a buck in just the past month. In some parts of Europe, prices at the pump have risen to 2.50 euros per liter, or the equivalent of more than $10 a gallon.

The problem could keep escalating based on historical patterns. Unlike gasoline-whose use peaks in the summer-diesel is in highest demand during colder months. It's used heavily by farmers during the harvest season and is also used for heating in some areas, including the Northeastern U.S.

Up until now, most analysts have been bullish on refiners, which are earning record margins making diesel. But given the scale of the price surge and its impact on the wider economy, some are starting to get nervous. Jefferies analyst Lloyd Byrne downgraded top U.S. refiners Valero and Marathon Petroleum to Hold from Buy late on Monday. Those two stocks are up 200% on average in the past 24 months.

They aren't really at risk from new supply coming into the market and taking their customers, because it takes years to build a refinery. But they could be at risk on the demand side. The higher prices go, the more likely people are to use less diesel, or governments are to impose some form of rationing. Already some countries in Asia have imposed rations on diesel. Indonesia even said it stopped importing diesel, switching to fuel produced locally from palm oil.

In the U.S., diesel consumption has lately been falling. It's down 3% from a year ago and 8% from two years ago, according to the Energy Information Administration's weekly data releases.

There are also growing calls for a ban on diesel exports from the U.S. Republican Senate candidates in Iowa and Michigan are backing a pause in exports, arguing that it could reduce prices at home.

The energy industry and the Trump administration have pushed back on the idea so far. Energy CEOs say that the U.S. already makes more diesel than the country needs for everyday use, so banning exports wouldn't unlock new supplies for American consumers. The ban could, however, convince some refiners to curb their own supply, because they would no longer have access to export markets. And those curbs could lead to longer-term shortages.

"Export bans are usually quick to go into place and slow to unwind, bringing lasting damage," wrote Patrick De Haan, head of petroleum analysis at GasBuddy.

Nonetheless, lawmakers representing farm states have backed the initiative, hoping it could offer some short-term price relief. Byrne said it's worth taking the possibility seriously.

Refining stocks are now priced for perfection. It wouldn't take much to knock them down a peg.