Is it really that likely?

[BrePerkins22]

In the midst of trying to understand why I feel like such **** ex: constant fatigue, lightheaded.. etc. My husbands grandmother (a type 2 diabetic for many years) decided to check my blood sugar levels with the little monitor thing.. (sorry, I'm not even sure what its called) It said my level was 155.  Could something have affected this like food I ate that day, or should I truly be concerned. She looked at me with this look that absolutely terrified me.  

[WaveRider]

See your doctor for glucose [blood sugar] testing to rule out diabetes. Thyroid disorders can affect pancreas insulin production. Insulin is needed to control your blood sugar.

The glucose tests are:
OGTT - Oral glucose test. You are given a sugary liquid to drink.
Fasting - Simple blood test
A1c - The gold standard for diabetes testing

"the little monitor thing"
Home glucose [blood sugar] meter. Geeks say glucometer, everyone else the former.

"It said my level was 155."
Depends on when this was done. Random testing has no meaning. Before meals and 2-3 hours after meals are test times. If it was 2-3 hours after a meal you are normal. That look could have been "I don't know?".

"constant fatigue, lightheaded.. etc"
The only way to now for sure is testing. Its possible you are experiencing Adrenal fatigue.
http://thyroid.about.com/cs/endocrinology/a/adrenalfatigue.htm

[concerned621]

Everyones blood sugar fluctuates. Foods, drinks can elevate blood sugar. Take it a few times a day 1 hour before a meal.  If should be under 100.  Mine usually runs 55. My husband is diabetic II, he runs 130-150 that's on meds and watching what he eats. Drinking no soda, watching any sugar intake. Always see a doctor if you think there is a problem.

Irritability, fatigue, excessive thirst are good indicators something is wrong.