An analysis of the relative risk for goitre in euthyroid patients with type 2 diabetes.

AIM: To assess the relative risk for goitre in a cohort of euthyroid patients with type 2 diabetes with special reference to the use of metformin and insulin therapy.

PATIENTS AND METHODS: Eight hundred euthyroid patients with type 2 diabetes (433 women, mean age 65·8 ± 12·5 years) and 671 euthyroid subjects without diabetes were retrospectively evaluated. There were 250 patients on metformin and 455 patients on insulin treatment.

RESULTS: The gender-, age-, body mass index- and thyrotropin (TSH)-adjusted relative risk for goitre occurring among diabetic patients relative to controls was 3·01 (1·61-5·64) (P < 0·01). This odds ratio was significant in females, patients with and without metformin therapy, patients without insulin therapy and without micro- and macrovascular complications of diabetes. However, male pateints, patients on insulin therapy or with micro- or macroangiopathy did not exhibit an increase in the risk of goitre. Patients on metformin therapy showed a significant increase in the risk of goitre only in the absence of insulin therapy. Multi-adjusted logistic regression analysis showed that goitre was significantly related to gender, TSH and haemoglobin A1c levels. Metformin and insulin therapy were nonsignificant variables in this model.

CONCLUSION: This is the first survey analysing the relationship between the presence of palpable goitre and clinical parameters in a large cohort of patients with type 2 diabetes. Our data suggest a significant relationship between goitre and glycaemic control, but do not support the presence of independent and significant relationships between goitre and metformin or insulin treatment in euthyroid patients with type 2 diabetes.