To offset a looming state budget gap, Massachusetts Gov. Deval Patrick will propose shifting more of the cost of health insurance premiums onto tens of thousands of state employees. Under the plan, about 37,000 employees would see their monthly premiums increase by 10 percent. Patrick also plans to require the purchase of more generic drugs in the state Medicaid program, and wants to cut Medicaid reimbursements to some hospitals and doctors for additional savings, according to officials.