The relationship between subclinical hypothyroidism and diabetic retinopathy in elderly type 2 diabetic patients / 中华老年医学杂志

ABSTRACT

Objective To investigate the relationship between subclinical hypothyroidism (SCH) and diabetic retinopathy (DR) in elderly type 2 diabetic patients.Methods 1170 hospitalized patients with type 2 diabetes mellitus were enrolled in our study.After identified by systematic sampling,all the elderly patients received examinations of thyroid function,biochemical indexes,steamed bread meal test and C-peptide releasing test.The serious degree of DR was observed through digital fundus photography and ophthalmofundoscope.The relationship between SCH and DR was analyzed.Results All the subjects were divided into two subgroupseuthyroid group(TSH≤4mU/L)and subclinical hypothyroidism (SCH) group (mild SCH group,TSH ＞4～10 mU/L; serious SCH group,TSH＞10 mU/L).Free thyroxine (FT4) was significantly lower in SCH group than in euthyroid group[(13.91±2.17) pmol/L vs.(16.55±2.81)pmol/L,P＜0.001].The levels of basal (CP0) and post glucose-challenge (CP1-3) C-peptide were significantly higher in SCH group than in euthyroid group (P0-3 value0.001,0.012,0.004,0.001).There were significant differences in the progress of diabetic retinopathy between SCH and euthyroid groups (retinopathy-L,P=0.018; retinopathy-R P=0.013).Conclusions Elderly type 2 diabetic patients with SCH have a higher incidence of diabetic retinopathy (DR).The elevated FT4 level and decreased basal C-peptide level are probably the main reasons.