UnitedHealth Group Inc. has warned that government funding cuts will make it hard to hit the top end of its 2013 earnings forecast. Investors will want to know if that warning still stands when the nation's largest health insurer reports second-quarter results Thursday.

WHAT TO WATCH FOR: UnitedHealth CEO Stephen Hemsley said in April that reimbursement cuts to the government's Medicare Advantage program amounted to "a significantly greater rate setback than anyone could have expected," and they will present a challenge to the company this year and next.

UnitedHealth is the nation's largest provider of Medicare Advantage plans, which offer government-subsidized coverage for elderly and disabled people. The insurer has nearly 2.9 million people enrolled in the plans, and they brought in about 20 percent of its revenue last year.

Funding for Medicare Advantage plans will be cut as part of the health care overhaul, which aims to provide insurance coverage to millions of uninsured Americans. The plans also took a hit earlier this year from other federal budget cuts.

UnitedHealth has said it may have to trim benefits, change provider networks or leave some markets to preserve the profitability of its plans.

The Minnetonka, Minn., insurer said last November that it expected 2013 earnings of between $5.25 and $5.50 per share, and it has since stuck with that forecast.

Analysts currently expect UnitedHealth to earn, on average, $5.43 per share this year, according to FactSet.

Nearly two months after UnitedHealth issued its warning, the insurer hiked its quarterly dividend by 32 percent. It cited its growth and consistent financial performance.

WHY IT MATTERS: UnitedHealth is the largest U.S. health insurer and the first to announce earnings every quarter. Many analysts and investors view it as a bellwether for the managed care sector.

Health insurance is UnitedHealth's largest business, but it also operates segments that sell information technology services and perform pharmacy benefits management. UnitedHealth also is the largest provider of Medicare Advantage plans, which are privately run versions of the government's Medicare program for the elderly and disabled people.

Investors like that diversity, as well as the company's quarterly dividend, which it raised last month to 28 cents per share. That's more than double the quarterly payout of 12.5 cents per share that UnitedHealth initiated in 2010, when it became the first major insurer to offer more than a token dividend.

UnitedHealth shares have climbed more than 25 percent since closing 2012 at $54.24. The shares reached a new, all-time high price of $68.75 July 10, as the stock continued a growth streak that began after the company announced its dividend increase.

WHAT'S EXPECTED: Analysts forecast, on average, earnings of $1.25 per share on $30.52 billion in revenue, according to FactSet.

LAST YEAR'S QUARTER: UnitedHealth's 2012 second-quarter earnings climbed more than 5 percent to $1.34 billion, or $1.27 per share, while revenue rose 8.3 percent to $27.3 billion. Enrollment gains helped fuel that growth, while a continued moderation of health care use helped profitability.