Generally revise laws relating to insurance coverage relating to obesity prevention

This bill requires health insurance plans in Montana to cover medically necessary injectable medicines prescribed for adults with prediabetes, gestational diabetes, or obesity, including both on-label and off-label uses. Coverage applies to policies issued, renewed, or modified in the state, though Medicare Advantage prescription drug plans are exempt. To maintain coverage, patients must participate in a lifestyle management plan if their health plan provides advance written notice. The legislation also amends existing state insurance laws regarding group plan membership for retirees, legislators, and judges, allowing them to remain in group plans until Medicare eligibility under certain conditions.