"This quarter's results demonstrate our ongoing commitment to operational excellence across all of our lines of business … and the continuation of low utilization of medical services primarily in our commercial business," said Humana CEO Michael B. McCallister.

The slowdown in the use of health care services has helped spur strong performances by managed care companies. Analysts say consumers tend to cut back their use of health care after a recession by delaying elective procedures or skipping doctor visits.

Goldman Sachs analyst Matthew Borsch said in a note that Humana's results show medical cost trends remain a "dominant theme" for the sector.

"Our view remains that medical cost trend will remain moderate through 2013 but within that framework there is room for some stabilization in health-care utilization relative to (an) exceptionally low trend in 2010, which is bullish for managed care," Borsch wrote.

In premarket trading, shares of Humana added $4.42, or 5.9 percent, to $79.

For the three months ended June 30, Humana earned $460.3 million, or $2.71 per share. That compares to nearly $340.1 million, or $2 per share, last year. Revenue in the just-ended quarter was up 8.1 percent at $9.28 billion.

Adjusted income, which excludes the impact of favorable prior-year medical claims reserves, was $2.50 per share.

The performance beat Wall Street forecasts. Analysts predicted, on average, earnings per share of $2.05 on $9.28 billion in revenue.

Humana reported that quarterly pretax income from its retail segment totaled $503.1 million, up from $325.9 million a year ago, as its individual Medicare Advantage membership rose 10 percent to 1.6 million members at the end of the second quarter.

Medicare Advantage plans are government sponsored, privately-run programs offering comprehensive health coverage for seniors. It's become a lucrative venture for Humana — the second-largest provider of Medicare Advantage plans.

Membership in Humana's stand-alone Medicare prescription drug plans was up 41 percent from a year ago at 2.4 million members. Humana credited the upswing in part to its decision to team with retail giant Wal-Mart Stores Inc. to offer a Medicare prescription drug plan.

Membership in its individual specialty plans including vision and dental coverage was up 55 percent from a year ago.

Pretax income for its employer group segment was essentially flat at $108.4 million, compared to $107.8 million a year ago.

Group Medicare Advantage membership totaled 309,700 at the quarter's end, up 4 percent from a year ago. Group fully-insured commercial medical membership declined by 8 percent to nearly 1.2 million.

Humana reported a 73 percent surge in pretax income from its health and well-being services segment.

The increase was due to growth in the company's pharmacy business along with its recent acquisition of health care company Concentra Inc., which provides occupational medicine, urgent care, physical therapy and wellness services.