Thyroid Disease and Type 2 Diabetes

by Mary Shomon Patient Advocate

Type 2 diabetes is the non-autoimmune form of diabetes. Type 2 is the most common form of diabetes, and it’s estimated that up to 95 percent of diabetes falls into the type 2 category.

In type 2 diabetes, your pancreas may be unable to release enough insulin to handle the sugar in your diet. You may also release insulin, but your cells are incapable of responding to it. This condition is known as insulin resistance, or pre-diabetes. Having thyroid disease puts you at an increased risk of developing type 2 diabetes; the opposite is also true. It's essential, therefore, to understand the link between these two conditions.

How thyroid disease and type 2 diabetes are related

Having a thyroid condition puts you at higher risk of type 2 diabetes. According to the Diabetes Council, an estimated 36 percent of people with hypothyroidism and 12 percent of people with hyperthyroidism also have diabetes.

Hypothyroidism is a risk factor for type 2 diabetes, whether your hypothyroidism is congenital or results from Hashimoto’s thyroiditis, radioactive iodine (RAI) ablation, or thyroid surgery.

Specifically, the underlying endocrine imbalances of hypothyroidism — including weight gain, elevated blood sugar, and other hormonally-related issues — contribute to your increased risk of insulin resistance, which is a crucial marker for the risk of type 2 diabetes. Mild or subclinical hypothyroidism, as well as undertreated hypothyroidism — with a thyroid stimulating hormone (TSH) level at the higher end of the reference range — also increase your risk of developing type 2 diabetes.

For people diagnosed with type 2 diabetes, there is an increased risk of developing or having a diagnosed thyroid condition. According to the American Diabetes Association, if you have been recently diagnosed with type 2 diabetes, you should have a comprehensive thyroid evaluation, along with regularly scheduled thyroid monitoring.

Risk factors for type 2 diabetes

In addition to hypothyroidism — especially hypothyroidism with a high or high-normal TSH level — you are at higher risk of type 2 diabetes if you have any of the following risk factors:

  • Being overweight or obese

  • A high percentage of body fat, especially belly fat, or a large waist circumference

  • Lack of physical activity or exercise

  • A family history of type 2 diabetes

  • Being over the age of 45

  • Having a history of gestational diabetes

  • Having a history of polycystic ovarian syndrome (PCOs)

  • Ethnicity: African-Americans, Hispanics, Native Americans, and Asian-Americans

Signs and symptoms of type 2 diabetes

The signs and symptoms of type 2 diabetes include:

  • Increased or excessive thirst

  • A dry mouth, "cotton-mouth"

  • Frequent need to urinate

  • A high volume of urine

  • Feeling extremely hungry, even after eating

  • Mood changes, including anxiety and irritability

  • Weakness and fatigue

  • Blurry vision, visual disturbances, dry eyes

  • Itchy, dry skin

  • Frequent infections

  • Wounds that heal slowly

  • Numbness and tingling in your hands and feet

  • Erectile dysfunction or impotence in men

  • Unintended weight loss or weight gain, or difficulty losing weight

  • Nausea

How type 2 diabetes is diagnosed

Type 2 diabetes is diagnosed by the results of one or more of the following tests:

Fasting glucose, a test that measures your blood glucose level before eating. Prediabetes is diagnosed at a level of 100 to 125 mg/dl, and diabetes is diagnosed at 126 mg/dl or higher.

Hemoglobin A1C (HA1C), a test that measures your average blood glucose level over a two-to-three-month period. Prediabetes is diagnosed at 5.7 to 6.4 percent, and type 2 diabetes is diagnosed at a level of 6.5 percent or higher.

The glucose tolerance test, which tests your glucose level before and two hours after drinking a sugary liquid. Prediabetes is diagnosed if glucose is 140 to 199 mg/dl at two hours, and diabetes is diagnosed at 200 mg/dl or higher.

Tests to diagnose type 2 diabetes.

Treatments for type 2 diabetes

It is vital for anyone with a thyroid condition who is diagnosed with type 2 diabetes to optimize thyroid treatment. You should have tight control of your hypothyroidism, typically a TSH level below 2.5, and free T4 and free T3 levels that fall in the upper half of the reference range.

Pay attention to ensuring that your TSH level is not at the upper end of the reference range, where blood-sugar control is more difficult.

The medical treatment for diabetes is oral or injectable drugs that make your body more sensitive to insulin. These drugs include:

  • Metformin (Glucophage)

  • Dipeptidyl peptidase-4 inhibitor drugs (DPP-4 inhibitors) like sitagliptin (Januvia), linagliptin (Tradjenta), and saxagliptin (Onglyza)

  • Glucagon-like peptide 1 receptor agonist drugs, including exenatide (Byetta/Bydureon), liraglutide (Victoza, Saxenda), lixisenatide (Lyxumia), albiglutide (Tanzeum), dulaglutide (Trulicity), and semaglutide (Ozempic)

  • Thiazolidinediones (TZD drugs), including pioglitazone (Actos) and rosiglitazone (Avandia)

  • Sulfonylurea drugs, including chlorpropamide (Diabinese), glimepiride (Amaryl), glyburide (Glynase), glipizide (Glucotrol), glyburide (DiaBeta), glipizide (GlipiZIDE), and tolazamide (Tolinase)

In more severe cases, people with type 2 diabetes may require insulin treatment.

If you are obese and have a body mass index (BMI) above 25, your physician may recommend bariatric surgery (i.e., gastric bypass).

Lifestyle interventions for type 2 diabetes include:

  • Follow a low-carbohydrate, low-glycemic (low-sugar) or carbohydrate-controlled diet. Some of the dietary approaches and plans that may be effective at reversing prediabetes or managing type 2 diabetes include the Mediterranean Diet, the Paleo Diet, and the Rosedale Diet.

  • Increase your dietary fiber, aiming for 25 to 30 grams of fiber daily.

  • Get at least 7 to 8 hours of sleep nightly.

  • Regular exercise and physical activity

  • Stop smoking.

Integrative physicians recommend a number of supplements that may help promote healthy insulin production and sensitivity and help lower blood sugar. Some of the supplements that may help prediabetes and type 2 diabetes include:

  • Alpha-Lipoic Acid

  • Aloe vera

  • Cinnamon

  • Bitter melon

  • Milk thistle

  • Fenugreek

  • Gymnema

  • Ginger

  • Royal Abuta

  • Chromium

  • Magnesium

  • Vanadium

Note: if you are being treated for type 2 diabetes and experimenting with supplements, be sure to notify your physician, as your medication dosages may need to be changed if your blood sugar levels and insulin sensitivity improve.

Prediabetes and preventing type 2 diabetes

Type 2 diabetes does not develop suddenly. Typically, blood sugar levels slowly increase, and abnormal levels can be detected during a period known as “prediabetes.”

Prediabetes is reversible, and progression to full type 2 diabetes is usually preventable. To reverse prediabetes or prevent the onset of type 2 diabetes, you need to lower your blood sugar and increase your body’s sensitivity to insulin.

In addition to ensuring that you have optimal thyroid treatment, the research shows that you can lower your risk for type 2 diabetes by as much as half by doing two things:

  • Losing at least 7 percent of your body weight

  • Getting sufficient exercise or physical activity at least 30 minutes a day, five days a week

You should also follow the same lifestyle interventions outlined for type 2 diabetes, including:

  • Follow a low-carbohydrate, low-glycemic (low-sugar) or carbohydrate-controlled diet.

  • Increase your dietary fiber.

  • Get 7 to 8 hours of sleep nightly.

  • Stop smoking.

In some cases, physicians recommend the use of a type 2 diabetes medication like metformin (Glucophage) to help control blood sugar and prevent prediabetes from developing into type 2 diabetes.

An important note for autoimmune thyroid disease patients diagnosed with type 2 diabetes

If you have Hashimoto’s, thyroiditis, or Graves’ disease and are diagnosed with type 2 diabetes, there is a chance that you may actually have a different type of diabetes, known as Latent Autoimmune Diabetes in Adults, or LADA. LADA is sometimes called type 1.5 diabetes. Experts estimate that around 10 percent of adults who are diagnosed with Type 2 diabetes have LADA, and if you are under 35, the rate is higher at 25 percent.

If you have been diagnosed with type 2 diabetes, but fall into any of the following categories, it's especially important to get screening for LADA:

  • You have a personal or family history of any autoimmune disease.

  • You are underweight or at a healthy weight.

  • You are being treated for type 2 diabetes but are unable to achieve good glucose control, and still have elevated blood sugar or a high hemoglobin A1C level.

To test for LADA, your physician should order the C-peptide test, as well as the GAD antibody test. The treatment for LADA is insulin therapy.

Mary Shomon
Meet Our Writer
Mary Shomon

Mary Shomon is a patient advocate and New York Times bestselling author who empowers readers with information on thyroid and autoimmune disease, diabetes, weight loss and hormonal health from an integrative perspective. Mary has been a leading force advocating for more effective, patient-centered hormonal healthcare. Mary also co-stars in PBS’ Healthy Hormones TV series. Mary also serves on HealthCentral’s Health Advocates Advisory Board.