Humana reported $1.2 billion in first quarter net income as the company gets better control of medical cost trends in its Medicare Advantage plans.

Health insurer Humana on Wednesday reported lower-than expected medical costs in the first quarter, allaying investor concerns about the sector after bellwether UnitedHealth's disappointing financial results earlier this month.

While Humana affirmed its full-year profit outlook, which can be viewed as a positive in the current uncertain economic environment, quarterly revenue came up a bit shy, and the earnings outlook for the current quarter was below Wall Street projections.