The link between diabetes and thyroid disorders has been well established by various medical researchers. The thyroid gland is a small gland located in the neck region that secretes thyroid hormones, which helps regulate the body’s growth, development and metabolism. A dysfunction in the thyroid gland may lead to weight gain and therefore, affect the blood sugar levels in the body. Despite the established connection, these conditions are often left undiagnosed in the early stages and only identified once symptoms get evident.

How are blood sugar levels and the thyroid gland related?

There is a strong interrelation between the function of the thyroid gland and blood sugar levels. If the blood sugar levels rise or decrease below the normal range, the thyroid hormone is stimulated to rectify the same. A constant fluctuation in blood sugar levels exerts physiological stress on the thyroid gland increasing the risk of thyroid dysfunction in the long run. 

Patients with type 1 diabetes mellitus are more frequently diagnosed with underactive thyroid function due to a condition called Hashimoto’s disease and around 10% of the type 1 patients may develop Grave’s disease, an autoimmune disorder causing an overactive thyroid gland. Both diabetes and Grave’s disease have a genetic causative factor associated with them.

Diabetes in Patients with Hyperthyroidism

Hyperthyroidism occurs due to excessive secretion of the thyroid hormone, which is characterised by:

• Excessive sweating
• Rapid heart rate
• Trouble in concentration
• Tremors
• Weight loss
• Diarrhoea
• Breathlessness
• Changes in mood and anxiety

In hyperthyroidism, increased production of glucose from the liver and increased absorption by the intestines may lead to a rise in blood sugar levels.

The metabolism rate increases in hyperthyroidism, which leads to faster digestion of blood sugar medicine. As a result, the medicine does not last long in the body and blood sugar level increases. Hence, in diabetics with hyperthyroidism, the dosage of blood sugar medications is increased until the thyroid levels normalise. 

Diabetes in Patients with Hypothyroidism

There is decreased production of thyroid hormone in hypothyroidism which may be evident as:

• Fatigue
• Constipation
• Weight gain
• Low blood pressure
• Slow pulse rate
• Depression

The most commonly associated disorder with hypothyroidism is type 2 diabetes mellitus. Patients with hypothyroidism may experience a sharp shift from a prediabetic state to a diabetic state. An underactive thyroid may also lead to aggravation in a diabetic patient. The comorbidities like obesity, dyslipidemia, hypertension, high body mass index (BMI) may further increase the risk of diabetes in hyperthyroidism patients.

Thyroid-related diseases and T2DM are closely linked. Type 2 diabetes can be exacerbated by thyroid disorders, and diabetes can worsen thyroid dysfunction. Insulin resistance has been found to play a crucial role in both T2DM and thyroid dysfunction.

Dr. M.G. Kartheeka, MBBS, MD

Thyroid Diseases in Patients with Diabetes

Hyperthyroidism or hypothyroidism diagnosed in the 40s or 50s is more prevalent in diabetic patients than in non-diabetic patients. The high levels of blood sugar in patients with diabetes can mask the hyperglycemia, caused due to hyperthyroidism, which can prove to be fatal. Those with hypothyroidism are at a higher risk of developing type 2 diabetes. Approximately 10% of patients with hypothyroidism are diagnosed with diabetes. Patients with type 1 diabetes are more prone to an autoimmune thyroid disorder.  

Consequences of Untreated Patients with Diabetes and Thyroid Disorders

If the fluctuation of blood sugar levels in a patient with thyroid dysfunction goes unnoticed or if thyroid disorder in a diabetic patient remains undiagnosed, many health complications might occur. Weight gain, deranged lipid profile, tiredness, anxiety are a few commonly noticed symptoms which if left untreated can affect the overall health of the person.

Precautions

• Eat a well-balanced diet every 2 – 3 hours, including good sources of proteins. Vegetarians should include fruits, vegetables and pulses and non-vegetarians can rely on meat and eggs for proteins.
• Avoid eating refined carbohydrates and trans fat items like pasta, doughnuts, pastries, cookies, ice cream too frequently, as it may lead to a sudden rise in blood sugar levels and stress the thyroid gland.
• Manage your weight to the optimum levels. It will help in the prevention of complications.
• Keeping a regular check on your blood sugar levels can help in the early diagnosis of diabetes.
• Test your sugar levels if you have a thyroid disorder and thyroid hormone levels if you have diabetes soon after diagnosis. Repeat the tests at least once every two years to avoid complications. 

Insulin resistance is a factor that interlinks thyroid disorders and diabetes. Patients usually complain of worsening thyroid symptoms when their blood sugars are out of control and their diet and medications are not able to manage the symptoms. A follow-up is essential to check and do modifications for the medications since they both are endocrine disorders and closely linked.

Dr. Ashish Bajaj, M.B.B.S., M.D.

Conclusion

There is a great possibility of developing a thyroid disorder after getting diagnosed with diabetes and vice versa. As both the hormones are concerned with metabolic processes of the body, the other hormones of the body are also affected. This may lead to a wide array of complications. To avoid this, precautions such as lifestyle modifications and regular testing are vital.

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