ABSTRACT
Objective To investigate the impact of subclinical hypothyroidism (SCH) on macrovascular complications in elderly type 2 diabetic patients.Methods A total of 1170 hospitalized elderly patients with type 2 diabetes mellitus were enrolled in the study through systematic sampling and underwent testing for blood biochemical indicators, thyroid function and C peptide.Parameters for macro-vascular complications, including the ankle/brachial index (ABI), transcranial Doppler vascular ultrasound (TCD), electrocardiogram (ECG), ejection fraction (EF), history of coronary heart disease, and hypertension grading were also monitored.Results All the subjects were divided into two groups based on the thyroid stimulating hormone (TSH) level: the euthyroid group (4 mU/L≥TSH＞0.4 mU/L) and the SCH group (TSH＞4 mU/L), and the latter was further sub-grouped into the mild SCH group (10 mU/L≥TSH＞4 mU/L) and the severe SCH group (TSH＞10 mU/L).ABI was significantly decreased in SCH (R/L: 0.86/0.92, P＜0.01).Levels of basal C-peptide (CP0) and post glucose-challenge C-peptide (CP1-3) were higher in the SCH group than in the euthyroid group [(2.16±0.93)pg/L vs.(1.56±1.05)pg/L, (0.53±0.25)pg/L v, (0.38±0.37),(0.72±0.23) pg/L vs.(0.56 ±0.32) pg/L, (6.21± 2.69) pg/L vs.(4.46 ± 2.62) pg/L,respectively, P＜0.01 for all].EF was higher in the SCH group than in the euthyroid group[(70.87± 6.66)％ vs.(65.10 ± 8.08％), P＜ 0.01].There were no significant differences in other biochemical indicators, ECG, TCD, history of coronary heart disease, hypertension grading and intervention treatment (P＞0.05 for all).Conclusions Lower extremity atherosclerotic disease has a higher incidence in elderly type 2 diabetic patients with SCH and occurs earlier than other macrovascular complications.Elevated TSH levels and insulin resistance may be the major causes.