Subclinical Hypothyroidism and the Associations with Macrovascular Complications and Chronic Kidney Disease in Patients with Type 2 Diabetes

AimsThe prevalence of subclinical hypothyroidism (SCH) is high among patients with diabetes, although the relationship between SCH and diabetic vascular complications is unknown. This study aimed to determine the relationship between SCH and vascular complications in patients with Type2 diabetes.MethodsIn this cross sectional study, 991 patients with Type2 diabetes were screened for thyroid function at their admission to the Second Affiliated Hospital of Chongqing Medical University. We compared the prevalence of coronary heart disease (CHD), ischaemic stroke and chronic kidney disease (CKD) with the prevalence of euthyroidism and SCH.ResultsAmong the 991 patients, 126 (12.7%) patients had SCH. The prevalence of CHD was significantly higher in the SCH group than in the euthyroid group (22.2% and 15.0%, respectively; P=0.039). In the logistic regression analyses, SCH was associated with CHD [odds ratio (OR): 1.993; 95% confidence interval (CI): 1.135-3.497; P=0.016]. This association was stronger in patients aged 65years than in younger patients [2.474 (1.173-5.220); P=0.017]. No significant association was found between SCH and ischaemic stroke. Patients with severe SCH had a high risk of CKD [1.842 (1.120-3.029); P=0.016].ConclusionsThis study provides evidence that SCH in patients with Type2 diabetes is associated with a high prevalence of CHD (and CKD in severe SCH), although not with ischaemic stroke.What's new?Owing to the paucity of data regarding the prevalence of subclinical hypothyroidism and its potential association with vascular complications in patients with Type 2 diabetes, the effect of subclinical hypothyroidism on the prevalence of coronary heart disease, ischaemic stroke and chronic kidney disease remains a controversial issue. This study provides evidence that subclinical hypothyroidism in patients with Type2 diabetes is associated with a high prevalence of coronary heart disease (and chronic kidney disease for severe subclinical hypothyroidism), although not ischaemic stroke. The findings indicate that patients with Type2 diabetes should be screened for thyroid function, especially patients with a high risk of coronary heart disease and chronic kidney disease.