March 14, 2004
Thyroid, Tight Control
Question from Edmonton, Alberta, Canada:
Through diet and exercise I have lost 75 pounds and have been able to reduce the amount of medication I have needed, giving me have pretty tight control of my blood sugars. I was also taking Synthroid, 150 mg, once a day. On my last test, my doctor said that my thyroid is on the low side of normal and increased my dosage to 175 mg. That was about a week ago and since that time my sugars have jumped from around 6.0 mmol/L [108 mg/dl] to the around 7.5 mmol/L [135 mg/dl]. Although this is still acceptable, it is not as low as I would like. Does the Synthroid affect the blood sugars? Wouldn’t I be better to have my thyroid on the “low side of normal” with lower blood sugars?
Answer:
It is possible that, in situations of marked hyperthyroidism, which may occur because of too much thyroid being prescribed or too much being made by an intact thyroid, blood sugars may rise. However, this was probably a small adjustment from your previous dose. In addition, it takes up to six weeks for the change in thyroid dose to achieve usual levels. Having symptoms within the week of the change is unlikely to be the cause of the blood sugar changes.
JTL
