Association of thyroid function within the normal range with glycemic control and cardiovascular risk factors in type 1 diabetes.

BACKGROUND

Thyroid hormone (TH) variations, even within the normal range, influence cardiometabolic health. In type 1 diabetes (T1D), optimizing glycemic control and cardiovascular risk is crucial to prevent complications. We aim to explore the association of TH within normal range with cardiometabolic profile in T1D.

RESEARCH DESIGN AND

METHODS

Cross-sectional analysis including adult patients with T1D followed at our Endocrinology Department between 2022-2024. We excluded patients with TSH or fT4 outside the reference range. Associations between TH (TSH, fT4, fT3 and fT3/fT4 ratio) and glycemic, anthropometric, and cardiometabolic parameters, were evaluated using linear regression models unadjusted and adjusted for relevant variables. Restricted cubic splines between TH and glycemic control parameters were performed to assess non-linear associations.

RESULTS

We included 296 patients (median age 35 years, 42.6% female). Patients with mid-range TSH had better glycemic control, with higher time in range and a lower time above range. Waist circumference and body mass index were negatively associated with fT4, and positively with fT3 and fT3/fT4 ratio. Estimated glomerular filtration rate was negatively associated with TSH and fT4, and positively with fT3 and fT3/fT4.

CONCLUSIONS

Variations in TH within the normal range were associated with glycemic control and cardiovascular risk factors in T1D.