Korean J Intern Med.  2016 Jul;31(4):703-711. 10.3904/kjim.2015.198.

Poor glycemic control is associated with the risk of subclinical hypothyroidism in patients with type 2 diabetes mellitus

Affiliations
  • 1Department of Internal Medicine, Yeungnam University College of Medicine, Daegu, Korea. kcwon@med.yu.ac.kr
  • 2Department of Internal Medicine, Kyungpook National University School of Medicine, Daegu, Korea.

Abstract

BACKGROUND/AIMS
Overt hypothyroidism is frequently found in patients with type 2 diabetes mellitus (T2DM), but it remains unknown the relationship between subclinical hypothyroidism (SCH) and T2DM. We attempt to evaluate the difference in prevalence of SCH between patients with T2DM and general population, and the association between SCH and glycemic control status ofdiabetic patients.
METHODS
This was cross-sectional study. Total 8,528 subjects who visited for health check-up were recruited. SCH was defined as an elevated level of serum thyroid stimulating hormone (> 4.0 mIU/L) with a normal level of free thyroxine. T2DM group was categorized into three groups by glycosylated hemoglobin (HbA1c): < 7% (reference), ≥ 7% and < 9%, ≥ 9%.
RESULTS
Finally, 7,966 subjects were included. The prevalence of SCH was not different between healthy controls and subjects with T2DM (8.1% vs. 7.4%, p = 0.533; in men, 5.7% vs. 5.1%, p = 0.573; in women, 10.9% vs. 11.7%, p = 0.712), but it was increased with highest HbA1c group more than well controlled group, especially in women. The risk of SCH was increased by group with poorer glycemic control; the odds ratio for HbA1c ≥ 9% compared to < 7% was 2.52 (95% confidence interval [CI], 1.09 to 5.86; p = 0.031), and 4.58 (95% CI, 1.41 to 14.87; p = 0.011) in women, but not significant in men.
CONCLUSIONS
The prevalence of SCH was similar between T2DM and healthy group. Poor glycemic control in T2DM was obviously associated with the risk of SCH, especially in elderly women. These results suggest SCH as comorbidity may be considered in elderly women with poor glycemic control.

Keyword

Subclinical hypothyroidism; Diabetes mellitus, type 2; Hemoglobin A, glycosylated

MeSH Terms

Aged
Comorbidity
Cross-Sectional Studies
Diabetes Mellitus, Type 2*
Female
Hemoglobin A, Glycosylated
Humans
Hypothyroidism*
Male
Odds Ratio
Prevalence
Thyrotropin
Thyroxine
Hemoglobin A, Glycosylated
Thyrotropin
Thyroxine
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