Prevalence of Thyroid Dysfunction in Autoimmune and Type 2 Diabetes: The Population-Based HUNT Study in Norway

J Clin Endocrinol Metab. 2016 Feb;101(2):669-77. doi: 10.1210/jc.2015-3235. Epub 2015 Nov 19.

Abstract

Context: Associations between autoimmune diabetes and autoimmune thyroid disease are known but insufficiently characterized. Some evidence suggests that type 2 diabetes may also be associated with hypothyroidism.

Objective: The objective of the study was to investigate associations of autoimmune and type 2 diabetes with the prevalence of hypo- and hyperthyroidism.

Design and setting: This was a cross-sectional, population-based study of adults in two surveys of the Nord-Trøndelag Health (HUNT) Study.

Participants: A total of 34 235 participants of HUNT2 (1995-1997) and 48 809 participants of HUNT3 (2006-2008) participated in the study.

Main outcome measures: Prevalence of hypo- and hyperthyroidism was estimated, assessed by self-report, serum measurements, and linkage with the Norwegian Prescription Database.

Results: In HUNT2, autoimmune diabetes was associated with a higher age-adjusted prevalence of hypothyroidism among both women (prevalence ratio 1.79, 95% confidence interval [CI] 1.30-2.47) and men (prevalence ratio 2.71, 95% CI 1.76-4.19), compared with having no diabetes. For hyperthyroidism, the corresponding cumulative prevalence ratios were 2.12 (95% CI 1.36-3.32) in women and 2.54 (95% CI 1.24-5.18) in men with autoimmune diabetes. The age-adjusted excess prevalence of hypothyroidism (∼6 percentage points) and the presence of thyroid peroxidase antibodies (8-10 percentage points) associated with autoimmune diabetes was similar in women and men. Type 2 diabetes was not associated with the prevalence of hypothyroidism. In HUNT3, associations were broadly similar to those in HUNT2.

Conclusions: Autoimmune diabetes, but not type 2 diabetes, was strongly and gender neutrally associated with an increased prevalence of hypo- and hyperthyroidism and the presence of thyroid peroxidase antibodies. Increased surveillance for hypothyroidism appears not necessary in patients with type 2 diabetes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Age of Onset
  • Aged
  • Cross-Sectional Studies
  • Databases, Factual
  • Diabetes Mellitus, Type 1 / complications*
  • Diabetes Mellitus, Type 1 / epidemiology*
  • Diabetes Mellitus, Type 2 / complications*
  • Diabetes Mellitus, Type 2 / epidemiology*
  • Female
  • Humans
  • Hyperthyroidism / complications
  • Hyperthyroidism / epidemiology
  • Hypothyroidism / complications
  • Hypothyroidism / epidemiology
  • Iodide Peroxidase / blood
  • Iodide Peroxidase / immunology
  • Male
  • Middle Aged
  • Norway / epidemiology
  • Prevalence
  • Sex Factors
  • Thyroid Diseases / complications*
  • Thyroid Diseases / epidemiology*
  • Thyroid Hormones / blood

Substances

  • Thyroid Hormones
  • Iodide Peroxidase