Let’s take a look at the important role of balanced blood sugar levels and your low thyroid symptoms Proper Blood Sugar levels are critical for anyone with low thyroid function. Normal blood glucose levels medically have a broad range of anywhere from 70 to 105. Almost all 'white' foods, like potatoes, rice, bread, pasta will raise your blood sugar. When your glucose levels climb, it's hard on your heart arteries which can and do lead to high blood pressure and other heart issues. When blood sugar levels decrease, the adrenal glands address this issue by secreting hormone cortisol. Then, the hormone sends a signal which tells the liver to produce higher amounts of blood sugar, thus bringing the levels of glucose to normal. The manufacturer warns diabetics that synthroid can affect glucose levels, but it fails to tell patients WHAT synthroid does. Given the preceding drug information that levothyroxine can potentially raise blood sugar, it would seem that the underlying problem was masked and even missed. Rather than solving the underlying metabolic dysfunction, the physician gave a medication that raised the blood sugar and appeared to be a successful treatment. Common Questions and Answers about Synthroid blood sugar synthroid I was put on 150 mcg of Synthroid for over a year and recently received a call from my doctor saying my levels were low and prescribed me 125 mcg of Synthroid. Usually the synthetic thyroid hormones don't raise blood sugar, but this may have elevated your T3 levels, and could be causing more gluconeogenesis for you, which typically will raise blood sugar. I know when I'm hypothyroid, pulse and blood pressure are lower than usual, so your faster pulse may well be a sign of being a bit hyper, and the diarrhea could be because of that, too. If you have high blood sugar (diabetes), Synthroid (levothyroxine tablets) may sometimes raise blood sugar. Talk with your doctor about how to keep your blood sugar under control. Talk with your doctor about how to keep your blood sugar under control. synthroid and blood sugar level. marley833. My mother has type 2 diabetes. She has recently been prescribed Synthroid. Her blood sugar levels have been erratic since. is this a possible side effect of synthroid? Thanks Read 1 Responses. Follow - 1. 1 Responses MEDICAL PROFESSIONAL Anita Ramsetty, MD. Hello, Synthroid itself as a medication does not often cause erratic blood sugars , but. Not only does it decrease insulin resistance and blood sugar levels in the body, another study by Kalra showed that it comes with a ‘thyroprotective’ effect. It means that the drug is able to reduce TSH levels in patients with hypothyroidism.