The economic slowdown has swelled the ranks of people without health insurance. But now it is also threatening millions of people who have insurance but find that the coverage is too limited or that they cannot afford their own share of medical costs.

Many of the 158 million people covered by employer health insurance are struggling to meet medical expenses that are much higher than they used to be  often because of some combination of higher premiums, less extensive coverage, and bigger out-of-pocket deductibles and co-payments.

With medical costs soaring, the coverage many people have may not adequately protect them from the financial shock of an emergency room visit or a major surgery. For some, even routine doctor visits might now take a back seat to basic expenses like food and gasoline.

“It just keeps eating into people’s income,” said James Corbin, a former union official who works for the local utility in Tucson.