The Connection Between Diabetes and Your Thyroid

Health Writer

A new study from the Netherlands suggests that having too little thyroid hormone circulating in the blood -- even at low-normal levels -- raises the risk of developing type 2 diabetes, especially in patients who already have pre-diabetes.

Risk factors for prediabetes

A diagnosis of prediabetes usually occurs when one's blood sugar level comes back elevated and further screening confirms the elevated level -- which nevertheless is still shy of a full diabetes diagnosis.  Prediabetes is considered a high-risk state for developing diabetes.  Risk factors for prediabetes include:

  • Being overweight or being diagnosed with obesity
  • Having a waist size greater than 35 inches (women) or 40 inches (men)
  • Being sedentary
  • Being older than age 45
  • Having a family history of diabetes (parent, sibling)
  • African-Americans, Hispanics, American Indians, Asian-Americans and Pacific Islanders all have a higher risk of prediabetes
  • History of polycystic ovary syndrome
  • Having certain sleep disorders like sleep apnea (often associated with obesity)

Other conditions “linked” to prediabetes include:

  • High blood pressure
  • Low levels of HDL (good cholesterol)
  • High levels of circulating triglycerides

Clearly some of these risk factors are modifiable, while others should inspire you to be committed to a healthy lifestyle to help counterbalance the strong risk factors that you can’t change.

Understanding your thyroidYour thyroid is a butterfly-shaped gland that sits at the lower portion of the front of your neck.  It has two lobes, and when it is a normal size your doctor cannot feel it.  The gland secretes several hormones.  During infancy and childhood having a healthy thyroid is crucial to normal brain development.  Hormones produced by the thyroid gland also influence metabolism, growth and development, and body temperature.  The thyroid can develop a number of diseases.  Among them, hypothyroidism occurs when the thyroid gland puts out lower-than-normal levels of thyroid hormones, while ** hyperthyroidism** occurs when the thyroid becomes overactive.

The study

The lead investigator in the Netherlands study, Layal Chaker, MD, of Erasmus Medical Center, Rotterdam, enlisted 8,452 subjects 45 years of age or older, with an average age of 65. Participants had blood tests to measure baseline blood sugar levels and thyroid function.  They were then followed every two to three years to check for development of type 2 diabetes and medical records were reviewed.  Over an average follow-up period of eight years, 1,100 participants developed prediabetes and 798 subjects developed type 2 diabetes.

Researchers noted a correlation between low thyroid function and risk of developing prediabetes and diabetes.  This was not surprising, given the link between thyroid function and metabolism.  The researchers were, however, surprised to find that even patients whose thyroid levels were “low normal” had 1.4 times elevated risk of progressing from prediabetes to diabetes.

Specifically, the risk of developing type 2 diabetes over the long term was increased by 13 percent in subjects with hypothyroidism.  In subjects who already had a diagnosis of prediabetes, the risk of developing diabetes was increased by 40 percent if they also had reduced thyroid function.

Health experts know that there are people walking around with undiagnosed subclinical hypothyroidism (mildly low thyroid function).  Based on this study, those people are unknowingly at a higher risk for prediabetes and diabetes.  The only way to identify these individuals would be with a screening blood test.  Dr. Chaker feels that future studies should investigate the value of screening for and treating subclinical hypothyroidism.

Symptoms of hypothyroidism

It’s important to recognize the symptoms of hypothyroidism.  They can include:

  • Dry skin
  • Fatigue
  • Constipation
  • Depression
  • Sensitivity to cold
  • Slower heart rate
  • Dry hair and hair loss
  • Noticeable swelling of the thyroid gland
  • Unexplained weight gain or difficulty losing weight

If you suspect that you have hypothyroidism or think that you are at risk, speak with your health care professional.  He or she can assess your symptoms and decide if a blood test to screen for the disease is appropriate.

See More Helpful Articles:

Dissecting Nutrition Labels

If Your Doctor Prescribes Fruits and Vegetables....

Hypothyroidism and Diabetes


Amy Hendel, also known as The HealthGal, is a Physician Assistant, nutritionist and fitness expert.As a health media personality, she's been reporting and blogging on lifestyle issues and health news for over 20 years. Author of The 4 Habits of Healthy Families, her website offers daily health reports, links to her blogs, and a library of lifestyle video segments.