TRENTON, N.J. (AP) — For Bridgett Snelten, changing her health insurance meant enduring wild blood sugar swings, bouts of vomiting and weight gain.

The Sandy, Utah mother of two young girls has diabetes and has had to change health insurance plans three years in a row. Twice, new insurers wouldn't cover Trulicity, a once-a-week injected diabetes medicine she'd been taking that helped control her blood sugar tightly. Instead, they made her return to an inexpensive, twice-a-day injected diabetes drug she and her doctor knew didn't work for her.

Each time, blood sugar plunges caused the shakes, v...