July 30 (Reuters) - Humana HUM.N raised its annual profit forecast on Wednesday, as the U.S. health insurer bets on its efforts to rein in higher medical costs that have plagued the sector, sending its shares up nearly 5% in premarket trading.

The company is a top provider of Medicare Advantage plans under which the U.S. government pays private insurers a set rate to manage healthcare for people aged 65 and older, and those with disabilities.

The industry has been battling with persistently high costs for the last two years due to increased use of healthcare services across the government-backed plans.

However, Humana said its medical costs were in line with its expectations.

It reported a quarterly medical cost ratio - the percentage of premiums spent on medical care- of 89.7%, up from 88.9% a year earlier, but in line with analysts' estimates of 89.71%.

Humana now expects full-year profit to be about $17 per share, compared with its previous estimate of about $16.25. Analysts on average were expecting a profit of $16.38 per share.