Thyroid UK

Levothyroxine and blood sugar levels?

Usually when I have my bloods tested my glucose / sugar levels are between 4-6. However, I checked them today on a gadget my hubby has and the levels were 7.2 one hour after a meal. I thought that was a bit high so I checked it again 3 hours later I had some snacks before and the levels were 7.8. I know from what I have read that's still in range but it seems to be on higher end both times.

My question is can thyroid meds have an effect on sugar levels? Or thyroid alone a low TSH is 0.5?

3 Replies


Low thyroid hormone will effects sugar levels in that it may reduce pancreatic function so influencing the release of insulin and glucagon, slowing glucose absorption in the gut, the rate our cells uptake glucose, the response of insulin secretion and the clearance of too much in the blood.

Are you diabetic or have insulin resistance ? ? .. You can have too much sugar in the blood (insulin resistance) or too little sugar in the blood (hypoglycaemia)

A healthy snack (ie: cheese & apple, etc) shouldn't encourage large blood sugar elevations as the protein and fats will level things out (& keep you feeling full for longer.) Snacking on sugary things can encourage insulin resistance and mess up cortisol levels as every time you have a blood sugar drop, your adrenals will secrete cortisol to increase glucose, especially to the brain to stop you feeling light headed..

If continual (ie lots of sugary snacking) this extra cortisol can inhibit conversion of T4 - T3, cause thyroid hormone receptor insensitivity (meaning that even if T3 levels are high enough, they may not be able to bind normally to receptor sites) and suppress pituitary function.

Eating regular meals with protein, healthy fats and low GI carbs will encourage good blood sugar levels and thyroid function.

1 like

In order to get accurate blood glucose levels you need to do a fasting test, as your glucose levels can vary depending on when and what you've eaten - you said you had had a meal an hour before the first test, and a snack before the second. Any rise in blood glucose due to intake of food, drink, medication etc is transitory in someone who isn't diabetic. If a fasting test is above 6 then see your doctor; although there can be small variations between meters, reliable makes generally have results which are within a narrow range of each other.


Used to get blood sugars as high as 20. But the worst was hypo when it was 2. This would catch me out as it didnt seem related to last meal time. Since i had TT for cancer I have had no further episodes like that! Have no idea why??! Glad no further hypoglycemic episodes , which are unpleasent. Such complex System, the endocrine. Anyone else with similar ?


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