NEW YORK/WASHINGTON: U.S. insurance regulators and state attorneys general are lining up to scrutinize Aetna Inc's proposed US$33 billion takeover of rival Humana Inc for potential harm to consumers, complicating what is already expected to be a tough and lengthy review by federal antitrust authorities. Insurance commissioners in 18 states including Texas, Kentucky and Florida will study merger documents provided by Humana to determine whether the deal will harm competition and lead to higher insurance premiums or diminished access to healthcare providers, according to Reuters interviews with regulators and insurance experts.