Hypothyroidism?

When I eat a little sugar (like a mini frosted cupcake) it causes a huge sugar crash, like I need to nap. Is this a telltale sign of anything? I was diagnosed with hypothyroidism with my second son but it went away after my pregnancy… 8 years ago.
Oprah was talking about hypothyroidism not too long ago and I have many signs… just wondering if the sugar crash bit rings any bells with anyone. Thanks in advance!