07/31/2026
ANNIE’S PEARLS
Thyriod and Blood Sugar
If you are taking thyroid medication for hypothyroidism it may effect the blood test for diabetes. Hgb-A1C tests your average blood sugar over 3 months time. Thyroid medication effects the A1C causing a higher level. It is not elevated by your blood sugar. To verify an elevation in blood sugar, also do a fasting blood sugar and a fructosamine. Fructosamine measures blood sugar level over 2 weeks. If FBS and fructosamine are normal, then the elevation in Hgb-A1C is from the thyriod medication. If all are elevated then you do have a blood sugar issue.
Reference for your Practitioner Effects of thyroid hormone on A1C and glycated albumin levels in nondiabetic subjects with overt hypothyroidism Mee Kyoung Kim et al. Diabetes Care. 2010 Dec.