Buy a box of oat matza (Kestenbaum). Eat only the minimal possible shiur.
Use dry wine at the sedarim (this is halakhically preferable, anyways- to use unadulterated, pure, non-mevushal wine).
Eat meals centered around protein and green vegetables. Lots of salads with olive oil and lemon juice, a low carb Blanchard dressing (if you can find it), low carb vegetables, berries, fruits, all fresh foods. AB has Pesah low carb gefilte fish, IIRC.
The key is not to eat more matza than need be. The Kestenbaum matza will allow you to control blood sugar and is allowed even on OA.
If you use diet soda, there is plenty of that for Pesah, as well as seltzers. Water with lemon is always good.
Tuna with celery, cucumbers, lettuce, eggs with spinach and a little cheese, turkey cold cuts (watch for sugars), such as Hod Golan and Tirat Zvi, are all good ideas, too.
The low carb diet actually shtims nicely with Pesah.