Merck & Co. (MRK), facing generic competition in August to its top-selling asthma drug Singulair, reported second-quarter profit that beat analyst estimates on higher sales of the diabetes medicines Januvia and Janumet.Earnings excluding one-time items of $1.05 a share beat by 4 cents the average of 18 analyst estimates compiled by Bloomberg. Net income fell 11 percent to $1.79 billion, or 58 cents a share, from $2.02 billion, or 65 cents, a year earlier, the Whitehouse Station, New Jersey-based company said today in a statement. Revenue climbed 1.3 percent to $12.3 billion.