Thyroid Meds Increase Risk for Elevated Blood Sugar

By Dr. Linda J. Dobberstein, DC, Board Certified in Clinical Nutrition

April 27, 2015

Thyroid Meds Increase Risk for Elevated Blood Sugar
Twenty-two million people are on Synthroid (levothyroxine) today in the United States. Millions of others are on other thyroid medications like Armour. Patients are usually on these medications for life once they start. Hidden deep within the drug literature precautions is startling information about blood sugar risks. Thyroid medications may pose a risk to your blood sugar levels. Of the millions of individuals who are on thyroid meds, have you been informed of this risky possibility? If you are not aware of this potential hazard, this information is for you!

Managing health requires many things. Often you need to be a detective and dig deep within the literature and ask questions. This is indeed the case with thyroid medications. Hidden deep within thyroid medication literature is a surprising statement on the risk of elevated blood sugar levels. It is easily glossed over or not recognized at all. This information may not be present in the condensed version of drug safety information handed out by the pharmacist or on the online consumer versions for Synthroid or levothyroxine.

Drug Safety Sheet Information

Detective work on the topic of thyroid drug pharmacology provides this information. Abbvie Labs, the makers of Synthroid provide this statement on their website hidden deep within their professional literature in the miscellaneous section. “Addition of levothyroxine to antidiabetic or insulin therapy may result in increased antidiabetic agent or insulin requirements. Careful monitoring of diabetic control is recommended, especially when thyroid therapy is started, changed, or discontinued.”

The only other statement found within Synthroid/levothyroxine professional literature on this risk was “Levothyroxine has a narrow therapeutic index. Regardless of the indication for use, careful dosage titration is necessary to avoid the consequences of over- or under-treatment. These conditions include…glucose and lipid metabolism.” There is no further description or discussion of what the glucose and lipid metabolism consequences may be for people who are not diabetic.

Armour thyroid drug safety information states: “Diabetes patients – Armour Thyroid may affect your blood sugar. Check blood sugar levels closely.” The drug information sheet for the brand name Eltroxin and generic levothyroxine specifically states that “Levothyroxine raises blood sugar levels. For people with diabetes, this may result in an increase in the requirements for insulin or antidiabetes medications. Monitor your blood sugar more closely when starting or changing doses of this medication.”

These warnings are found only in the drug-drug interactions or miscellaneous sections for those on diabetic medications. The general adverse effects information, which is where most individuals look, has absolutely no mention of potential blood sugar consequence. Step back and think about this for a moment. If thyroid medications increase blood sugar levels in diabetics, what about non-diabetic patients who are on the same medication? Certainly blood sugar levels matter in terms of regulation and is relative to the context, but it requires awareness on the behalf of the doctor and all patients.

Possible Blood Sugar Responses

In various patient discussion groups, astute individuals who monitor their blood sugar have reported that blood sugar levels often rise 10-20 points after starting the thyroid med. The patients were not diabetic and they had an established fasting blood sugar of 80-85 to start which then jumped to 90-95 after the start of the thyroid medication. These lab values are still considered within normal blood sugar range. The values would be dismissed as related to diet, stress, or something else; but what about the big picture over time? Is this tolerable and health promoting?

If a person in their twenties starts on thyroid medication with normal blood sugar levels and remains on the med for several decades, how does the extra 10-20 points of blood sugar affect the body? It has the possibility of taking a toll that would normally be dismissed to aging or other factors. Senior citizens who have taken thyroid meds for life often struggle with type 2 diabetes, insulin resistance, chronic thyroid dysfunction, and weight gain. Is due to the disease process, diet and aging or is it hastened by the drug reaction?

This risk raises concerns for the medical professionals who treat thyroid symptoms aggressively and for those patients who have borderline concerns. The patient who is overmedicated or unnecessarily medicated may end up facing needless risks. These risks should be openly discussed. Remember that in most circumstances, once a person is on thyroid hormone medication for two years or longer, medication use is for life as the thyroid becomes dependant upon it. Is the aggressive management worth the risk of blood sugar dysfunction or can a gentler approach be taken?

A recent case study published in March 2015 puts an interesting spin on this topic. The study was entitled “Recurrent hypoglycemia in type 2 diabetic patient due to hypothyroidism.” The author discussed that a type 2 diabetic patient had trouble with low blood sugar. The low blood sugar was not due to medical overtreatment for diabetes, or other problems with liver or kidney health. The patient was found have problems with low thyroid function and was subsequently started on levothyroxine. The levothyroxine elevated the patient’s blood sugar to the point where hypoglycemia resolved and thyroid levels improved. The medical commentary and interpretation was that the levothyroxine normalized (elevated) the blood sugar because the thyroid was under functioning. On the first read through, the levothyroxine seems to be the cure because of faulty thyroid function. However, if you think about this from the context of levothryoxine raising blood sugar as a side effect, it creates a different spin.

In physiology, healthy thyroid function actually allows us to burn sugar and fat for energy at a proper speed, i.e. it helps lower blood sugar in response to meals taken in and metabolic need. Healthy blood sugar function as regulated by the adrenal glands, pancreas, and the hormone leptin must be present otherwise the thyroid stresses out. We want well-managed blood sugar, not increased risks for elevated blood sugar. 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.

Thyroid Meds and Statins – Disaster Waiting to Happen?

The intent of this article is to raise awareness that this number one prescribed medication may be subtlety contributing to the risks and onset of steadily increasing blood sugar problems and the diabetes epidemic. Consider this risk along with other medications like statins that people with hypothyroidism often take. Just a few years ago, the FDA admitted that statin cholesterol drugs caused increased blood sugar. Many people with hypothyroidism are on cholesterol lowering medications because cholesterol elevates in response to poor thyroid function. My concern is that the combination of these two drugs together may be a sly driving downward fall contributing secretly to the failing health in this country. Advertisements for class action lawsuits involving statins and diabetes have flooded the airwaves since 2013 when the connection was revealed. Will thyroid patients be facing this same concern in the future?

Take Charge of Your Hemoglobin A1C

The fact remains that the drug companies list blood sugar elevations as a risk factor for those who are on diabetic medications, but omits it from the list of general adverse effects. If you are on any thyroid medication especially long-term, you need to take charge of your health and your blood sugar. There are so many things that affect blood sugar regulation, but this seems to be a potentially large elephant in the room waiting to be awakened.

Everyone needs to know what their hemoglobin A1C and fasting blood sugar levels are before and any time after thyroid medication use. Get it checked at least once per year. If you have borderline or known problems with blood sugar and weight management, get it checked more frequently. If you take thyroid and/or statins, be proactive. Again, there are innumerable reasons for elevated blood sugar levels, but sometimes it is the hidden reasons that are the hardest to understand and resolve. Don’t let your physician dismiss you and your concerns. Optimal hemoglobin A1C levels are 4.8 - 5.5. Anything above 5.5, even when considered within normal reference range will negatively affect long-term neurological health. This was proven in a 2013 landmark study in the New England Journal of Medicine. Don’t become the senior citizen on bone loss, blood sugar, and dementia drugs after a lifetime of thyroid hormone replacement and wonder what caused the deterioration. Medication adverse effects gnaw away at health and are unfortunately often dismissed.

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