This is a big week for the future of American health insurance.

A mammoth offer from Aetna to buy Humana for $37 billion is setto be approved by shareholders this week, three months after thetentative deal was announced by company executives.

Shareholders will also vote on Centene's $6.3 billion offer forHealth Net. Both companies specialize in health plans throughgovernment-subsidized programs, including Medicare, Medicaid andthe Obamacare state insurance exchanges.

CNBC reports that independent proxy advisers, InstitutionalShareholders Service and Glass Lewis, recommended both deals basedon potential cost savings, and the belief that the newly-formedcompanies would be more efficient.

But while the Centene deal has already gotten the nod from thefederal Justice Departmentbut the Aetna-Humana deal could require asignificant amount of additional scrutiny from federal regulatorsbefore it is approved.

In evaluating the Aetna-Humana deal, regulators will try todetermine whether the merger, along with that of Cigna and Anthem,will negatively affect health care consumers. The concern is thattoo much consolidation of payers could limit options ––particularly in certain parts of the country –– and leave patientsand providers at the mercy of an insurancemonopoly.

A number of experts and industry groups have weighed in on thepotential pros and cons to the mergers. Whilebolstering the strength of one insurer can force competitors toprovide consumers better options, too much consolidation can leaveconsumers with no competition at all.