Association between thyroid dysfunction and insulin resistance: a retrospective cohort study

Abstract

Objective: To evaluate the association between thyroid disease and diabetes markers.

Design: Retrospective cohort study.

Setting: The study was conducted in a diagnostic setting where the primary care providers recommended the patients to test for thyroid and diabetes panels.

Participants: The thyroid and diabetes markers were tested in 32 787 subjects with suspected thyroid and related conditions who visited Vibrant America Clinical Laboratory between January 2015 and June 2019.

Results: Our general prevalence results showed that homeostatic model assessment-insulin resistance (HOMA-IR) was elevated in overt hypothyroid subjects (43.7%) and overt hyperthyroid subjects (42.2%). Glycated hemoglobin (HbA1C) was elevated in subclinical hypothyroid subjects (19.2%), overt hypothyroid subjects (22.3%) and overt hyperthyroid subjects (21.2%). Glucose was significantly elevated in subclinical hypothyroid subjects (24.2%) and overt hyperthyroid subjects (31.0%). Insulin was significantly elevated in overt hypothyroid subjects (15.1%). Interestingly, we found that 70.3% of subjects who had their HOMA-IR score escalated from negative (HOMA-IR<2.7) to positive (HOMA-IR>2.7) during their multiple visits had anti-thyroid peroxidase (anti-TPO) 369 (±242) days prior to the onset of this change.

Conclusion: Our findings showed that anti-TPO levels are elevated before the onset of insulin resistance, indicating its potential use as a predictive marker.

Keywords: DIABETES & ENDOCRINOLOGY; General endocrinology; Thyroid disease.

Figure 1. Prevalence of diabetes markers in subjects with different thyroid disease profiles compared with their controls (thyroid disease negative). Diabetes markers significantly elevated/reduced are only shown. HbA1c, glycated hemoglobin; HOMA, homeostatic model assessment,

Figure 2. The prevalence of different thyroid diseases, anti-TPO and anti-Tg prior to the onset of homeostatic model assessment-insulin resistance (HOMA-IR) elevation compared with their respective control groups. The thyroid control group consists of subjects who had thyroid disease-parallel, thyroid disease-following and no thyroid disease to the onset of HOMA elevation. Anti-TPO control group consists of subjects who had anti-TPO-parallel, anti-TPO-following and no anti-TPO to the onset of HOMA elevation. Anti-Tg control group consists of subjects who had anti-Tg-parallel, anti-Tg-following and no anti-Tg to the onset of HOMA elevation. Tg, Thyroglobulin; TPO, Thyroid peroxidase.