Endocrine Abstracts

Background and aim

Abundant evidence suggests an association between thyroid disease and type 2 diabetes mellitus (T2DM). To determine the interaction between these co-existing pathologies, we analyzed insulin-treated type 2 diabetes patients with diagnosed thyroid disease.

Patients and methods

This retrospective study was performed in 54 type 2 diabetes patients who had been admitted for insulin-treatment and diagnosed thyroid disease. Patients were divided into two groups: Group 1(G1) thyroid disease diagnosed after diabetes onset and group 2 (G2) thyroid disease diagnosed prior to diabetes onset.

Results

Among the 54 patients studied, 75.92% of participants were females and 25.92% had family history of thyroid disease. Sub-clinical hypothyroidism constituted 44.44% of the thyroid dysfunction in the T2DM patients, clinical hypothyroidism was 25.94% and hyperthyroidism was 29.62%. Thyroid disease was predominantly diagnosed after diabetes onset (G1: n = 42, 77.77%): Hypothyroidism was predominantly diagnosed after T2DM onset while hyperthyroidism was predominantly diagnosed prior to diabetes onset. BMI and HbA1c did not statistically differ among the two groups (30.47 kg/m² vs 29.22 kg/m², 11.21% vs 11.16% respectively). G2 patients were older at diabetes onset (53.33 years vs 44.21 years, P = 0.01) and were younger at thyroid disease onset than G1 patients (48.91 years vs 52 years, P = 0.38). Patients with type 2 diabetes and prior appearance of thyroid disease(G2) required insulin therapy significantly earlier with median insulin-free period of 4 years compared to patients who had thyroid dysfunction after diabetes onset(G1) with median insulin-free period of 8.07 years, P =0.01 Group 1 patients (thyroid after diabetes) developed thyroid disease on average only after the initiation of insulin treatment. However, a clear negative correlation was observed between age at diabetes onset and insulin-free period (r = - 0.3, P  = 0.05). The older the patient the sooner insulin treatment was started.

Conclusion

Patients with thyroid disease prior to T2DM required significantly earlier insulin therapy compared to patients without thyroid diseases at the time of diabetes onset. Further studies are needed to elucidate mechanisms of interaction of thyroid disease in type 2 diabetes patients.