Association of age, BMI and their interaction with thyroid nodules in patients with type 2 diabetes mellitus: a...

Type 2 diabetes mellitus (T2DM) and thyroid nodules are both prevalent endocrine conditions; the prevalence of comorbidity between the two continues to rise. However, the independent and interactive effects of age and body mass index (BMI) on the development of thyroid nodules in patients with T2DM remain unclear. The objective of this study is to examine the correlation between age, BMI, and their interaction with the risk of developing thyroid nodules in patients with T2DM.

A retrospective study encompassed 720 hospitalised T2DM patients. The patients were divided into two groups based on the findings of thyroid ultrasound scans: a thyroid nodule group (n=599) and a non-thyroid nodule group (n=121). A comparison was made between the baseline clinical characteristics of the two groups. Univariate and multivariate logistic regression analyses were performed to identify independent risk factors for thyroid nodules, and stratified analyses and interaction tests were conducted to assess the interaction between age and BMI.

Multivariate logistic regression analysis showed that age was an independent risk factor for thyroid nodules in patients with T2DM (P<0.001), and the risk of thyroid nodules in patients aged 45-60 years and ≥60 years was 5.12 times and 9.07 times that of patients aged <45 years, respectively. BMI was an independent protective factor (P<0.05), and the risk of thyroid nodules in patients with BMI 24-28 kg/m² and ≥28 kg/m² was 0.52 times and 0.46 times that of patients with BMI <24 kg/m², respectively. There was a significant interaction between age and BMI (OR = 1.26, 95% CI: 1.08-1.47, P = 0.003). Stratified analysis showed that in the subgroup with BMI ≥24 kg/m², the promoting effect of age on thyroid nodules was more obvious; in the subgroup aged <45 years, the protective effect of BMI was more prominent; in the subgroup aged 45-60 years, BMI ≥28 kg/m² became a risk factor (OR = 8.30, 95% CI: 1.42-48.56, P = 0.019).

Age and BMI have independent and interactive effects on the risk of thyroid nodules in hospitalised T2DM patients. However, the findings may not be generalizable to community-dwelling or outpatient T2DM patients without further validation.