Please register to participate in our discussions with 2 million other members - it's free and quick! Some forums can only be seen by registered members. After you create your account, you'll be able to customize options and access all our 15,000 new posts/day with fewer ads.
Thyroid disease is conducive to blood sugar issues, hypoglycemia and pre-diabetes. In some medical traditions, hypoglycemia is considered an incipient pre-diabetic condition: the first stage in a continuum leading to diabetes. In any case, it sounds to me like the OP is getting an insulin spike from his ingestion of carbs, followed by a crash, which is the hypo phase. That's the typical pattern in pre-diabetes, and it's remedied by cutting back on carbs and including sufficient protein with each meal and snack to balance the metabolic hormones to prevent the spike and crash cycle.
Skipping meals or delaying too much before the next meal can also bring on hypoglycemia in individuals with poor blood sugar control, which would describe the OP, as a thyroid patient. Having protein snacks in-between meals keeps the blood sugar stable.