ASSOCIATION BETWEEN SUBCLINICAL HYPOTHYROIDISM AND DIABETIC RETINOPATHY IN TYPE 2 DIABETIC PATIENTS
Objectives: To determine the association between subclinical hypothyroidism and diabetic retinopathy in type 2 diabetic patients.
Study design: Case control study.
Place & Duration of Study: Department of Chemical Pathology & Endocrinology, Armed Forces Institute of Pathology Rawalpindi, from September 2013 to June 2014.
Materials & Methods: A total of 436 diabetic subjects of either gender, aged 30 - 65 years were consecutively enrolled. 218 subjects with diabetic retinopathy (DR) were taken as cases (group A) while similar number of patients without DR were taken as controls (group B); with HbA1c > 6.5 % and duration of diabetes at least >5 years for both the groups. Known patients of type 1 diabetes mellitus (T1DM), hypertension, pregnancy, chronic renal failure and chronic liver disease, known thyroid disease were excluded from the study. HbA1c was measured on Modular p800 by turbidimetric inhibition immunoassay. Serum free T4 and serum TSH were measured on IMMULITE®2000 by chemilumiscence immunoassay. SCH was compared between case and control groups using chi square test. Odds ratio was also calculated for SCH. p value <0.05 was considered statistically significant.
Results: Cases (group A) had higher mean serum TSH as compared to controls (group B). SCH was diagnosed in 87 individuals (53 cases and 34 controls). Overall prevalence of SCH was 19.9% (24.3% in group A and 15.6% in group B). Chi square test revealed significantly higher prevalence of SCH in group A (p value 0.023). OR was 1.738 (CI 1.129 – 2.917).
Conclusion: There was significant association between SCH and DR in type 2 diabetic patients.
Key words: Diabetic retinopathy, Subclinical hypothyroidism, Type 2 diabetes mellitus.