Diabetes Forecast

What You Need to Know About Thyroid Disorders

By Matt McMillen , ,

Azurhino/Thinkstock (butterfly); jacoblund/Thinkstock (woman)

Maren Lynch was exhausted. She had always been full of energy and game for a night out, but over the course of a few months, her fatigue took over her life. She stopped meeting friends after work, preferring, instead, to go home and crash on her couch. On weekends, she often napped during the day even though she was sleeping 14 hours a night. Her plummeting energy—never mind the toll it was taking on her social life—wasn’t her only concern. She couldn’t think straight.

“I had brain fog,” says Lynch, a medical assistant who lives outside Chicago. “I couldn’t get words out, even though I knew what I wanted to say.” Her ease with spreadsheets and math disappeared. “I kept inverting numbers and could barely add or subtract,” she says.

Making matters worse, she couldn’t keep her weight down.

She lived with her symptoms for almost a year before concerned friends convinced her to take her troubles seriously. After investigating her symptoms online, she requested a simple blood test at the doctor’s office where she worked. It confirmed her suspicions. At 28, Lynch had an underactive thyroid. 

The Basics

Your thyroid is a small, butterfly-shaped gland located at the base of your neck. It produces thyroid hormone, which regulates various bodily functions, such as heart rate, energy levels, body temperature, and bowel function. Thyroid disease can result in hypothyroidism, in which the thyroid produces too little thyroid hormone, or hyperthyroidism, in which it produces too much. 

In the United States, just over 1 percent of people 12 and older have hyperthyroidism, while hypothyroidism occurs in nearly 5 percent of Americans in the same age range. Both of these endocrine disorders occur much more often in women than men, and the risk of hypothyroidism rises with age.

The Diabetes Connection

Hypo- and hyperthyroidism are often the result of autoimmunity, in which the body’s immune system attacks healthy tissues and organs. Type 1 diabetes is an autoimmune disease, and having one autoimmune disease raises your risk of developing another. That explains why people with type 1 diabetes have an increased risk for autoimmune thyroid disease. As many as 30 percent have a thyroid disorder, according to the 2018 Standards of Medical Care in Diabetes from the American Diabetes Association (ADA).

There’s also a link between thyroid conditions and types of diabetes that aren’t autoimmune disorders. For instance, low levels of thyroid hormones may increase a woman’s risk of gestational diabetes, according to a study published in a 2016 issue of the Journal of Clinical Endocrinology & Metabolism. And an estimated 12 percent of people with type 2 diabetes also have thyroid disease, though the relationship between the two isn’t well understood. In a study published in a 2016 issue of BMC Medicine, however, researchers reported that an underactive thyroid appears to raise the risk of type 2 diabetes, especially for people who already have prediabetes. People like Maren Lynch.

Not long after she discovered she had hypothyroidism, Lynch learned she had prediabetes. Throughout her 20s, blood tests done as part of her annual physical had shown an uptick in her fasting blood glucose levels. At age 30, she was diagnosed with type 2 diabetes.

The Screening

The ADA recommends screening for thyroid problems soon after a diagnosis of type 1 diabetes, once your diabetes is well managed. It’s a simple procedure. A blood test that measures your level of thyroid-stimulating hormone (TSH) will reveal any abnormalities. If your TSH level is normal, your doctor will test you every year or two to make sure it stays that way. The ADA currently has no specific screening guidelines for people with type 2 diabetes.

Betul Hatipoglu, MD, an endocrinologist at the Cleveland Clinic, worries that too few people with diabetes get screened for thyroid problems. Sandra Arévalo, MPH, RDN, CDE, agrees. “There needs to be more awareness,” says Arévalo, director of nutrition services and outreach programs and coordinator of diabetes management programs at Community Pediatrics, a program of Montefiore Hospital in the Bronx. “I’m always pushing for thyroid tests.”

An early diagnosis, before symptoms develop, may catch a thyroid problem before it begins to impact your diabetes management. “These problems can sneak up on you and wreak havoc,” says Gerald Bernstein, MD, coordinator of the Friedman Diabetes Program at Lenox Hill Hospital in New York City.

Untreated thyroid disease makes diabetes much more difficult to manage because of the way in which it disrupts metabolism. In fact, such difficulties frequently offer the first clues that a thyroid problem exists. “If someone gets hypoglycemia, or low blood glucose, more frequently than usual, for example, I will screen them for hypothyroidism,” says Hatipoglu. “It puts you at higher risk of low blood sugar and high cholesterol, while in some instances, it increases insulin resistance and makes it more difficult to control your blood glucose.”

Untreated hyperthyroidism can cause your blood glucose to rise, says Bernstein: “It revs up the metabolism, which increases the rate that food gets absorbed into the GI tract, and that drives blood glucose up.”


If you’re diagnosed with hypothyroidism, your doctor will start you on a once-daily pill, levothyroxine, which contains synthetic human thyroid hormone. Over several months of trial and error, your hormone levels will be tested and medication adjusted until your hormones measure in the normal range. After your proper dose has been established, your doctor will check your thyroid hormone levels once a year. You may eventually need a different dose because your requirements may change over time.

Many factors contribute to those changes, such as increasing age, weight gain, and the progression of your thyroid disease, says Bernstein. It’s a simple one-pill-a-day regimen, but you have to stick to it. “For most people, hypothyroidism is a chronic disease you’ll have to deal with for the rest of your life—just like diabetes,” says Arévalo.

Pregnancy puts a higher demand on your thyroid, which is why it’s critical you have your thyroid status checked before trying to get pregnant. Hatipoglu says that most women with an underactive thyroid will need to increase their dose while pregnant. They’ll need monthly tests throughout pregnancy to confirm their thyroid-stimulating hormone levels remain on target.

Treatment for an overactive thyroid depends on the cause and is often more complex than treatment for hypothyroidism. It may include medication, radiation therapy, surgery, or a combination of these. In some cases, hyperthyroidism resolves on its own.

Health Conditions

Maren Lynch, now 41, has been on the same dose of her thyroid medication for several years now. It took about four months to arrive at the right dose, but once she and her doctor got there, her life began to improve dramatically. “I felt my old self return as my energy levels went up,” she says. “It was like the fog had lifted.”

Her weight has remained a challenge, but Lynch thinks it has to do with entering middle age, when metabolism begins to slow and shedding excess pounds can become more difficult. Though her weight has not shifted as much as she’d like, her attitude has.

“I have stopped beating myself up when the number on the scale doesn’t move the way I want it to,” she says. “It’s taken many years to shift my mind away from the scale and focus on my overall health.”

Hyperthyroidism vs. Hypothyroidism


Most often, an overactive thyroid results from an autoimmune disorder known as Graves’ disease. In this condition, antibodies bind to the thyroid and activate it to produce more thyroid hormone. Benign, or noncancerous, growths on your thyroid can also lead to an overproduction of thyroid hormones.

The symptoms of hyperthyroidism include:

  • Sudden, unexplained weight loss
  • Rapid, irregular, or pounding heartbeat
  • Increased appetite
  • Tremors, particularly in your fingers and hands
  • Changes to your menstrual cycle
  • Sweating
  • Anxiety
  • Thinning skin
  • Diarrhea or an increased number of bowel movements
  • Irritability
  • Hair loss
  • Trouble sleeping
  • Trouble concentrating


An underactive thyroid is most often caused by an autoimmune disorder called Hashimoto’s disease (chronic lymphocytic thyroiditis). It occurs most commonly in women ages 40 to 60. It usually becomes worse with time, causing your thyroid to produce less and less thyroid hormone.

Hypothyroidism also can occur following treatments that address an overactive thyroid because those treatments can dramatically curb your thyroid’s ability to function. Radiation treatment for head and neck cancers can also lead to hypothyroidism.

The symptoms of hypothyroidism include:

  • Fatigue
  • Weight gain
  • Hair loss
  • Weakness
  • Elevated cholesterol
  • Memory problems
  • Erratic and/or heavier-than-usual menstruation

The symptoms can be vague and subtle. “It’s not always obvious that something is truly wrong,” says Betul Hatipoglu, MD, an endocrinologist at the Cleveland Clinic. “But in the long term, it may lead to heart disease, which is the thing I worry about. People with diabetes already have a high risk of heart disease, and untreated thyroid disease makes that risk even greater.”

Recognition of hypothyroidism is especially important in women who are planning to get pregnant. That’s because hypothyroidism may increase the risk of miscarriage, and it could impair the development of the baby’s brain. Because damage can be done early in the first trimester, women at risk for hypothyroidism—those with diabetes or a personal or family history of thyroid disorders—should have their thyroid checked before attempting pregnancy. For many women, mild hypothyroidism that began in pregnancy disappears a few months after they give birth, according to a study published in 2013 in the Journal of Clinical Endocrinology & Metabolism. But it can be permanent, says Gerald Bernstein, MD, coordinator of the Friedman Diabetes Program at Lenox Hill Hospital in New York City. “If there’s a propensity to thyroid disorder, it may be brought out during pregnancy.”



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