Abstract
Context: Thyroid hormone (TH) plays an important role in regulating glucose metabolism, but if TH in normal range could influence the glycemic variability in patients with type 2 diabetes (T2DM) has not been reported.
Objective: To determine the relationship between TH and glycemic variability in type 2 diabetes.
Methods: In this retrospective analysis, 468 inpatients with T2DM received continuous glucose monitoring (CGM) systems for 6-14 days. Baseline clinical characteristics, laboratory tests and CGM parameters were recorded to analyze the relationships between TH and CGM parameters.
Results: The levels of HBA, MG, SD, CV, LAGE, MODD, TAR2Scale were all higher and TIR was lower in FT3/FT4Q1 compared with FT3/FT4Q2, FT3/FT4Q3 and FT3/FT4Q4 (all P<0.01). Linear regression showed that FT3/FT4 ratio was negatively related with HBA (β=-2.056, P=0.034), MG (β=-2.461, P=0.045), SD (β=-1.365, P=0.038), MAGE (β=-2.718, P=0.041), MODD (β=-1.32, P=0.024) and TAR2Scale (β=-23.307, P=0.001). Smooth curve fitting and Saturation effect analysis showed that there were curve-like relationships between FT3/FT4 ratio and SD, MAGE, MODD and TAR2Scale, and the inflection points of the fitted curves were FT3/FT4=0.279, 0.237, 0.253 and 0.282 respectively (P<0.05), while there were linear relationship between FT3/FT4 ratio and HBA, MG and TIR (P<0.05). Binary logistic regression showed that FT3/FT4 ratio was independent related with HBA (P=0.001), MG (P=0.01), TAR2Scale (P=0.003), LAGE (P=0.014) and MAGE (P<0.001).
Conclusion: The level of FT3/FT4 ratio in a certain range (FT3/FT4 ≤ 0.282) is a protective factor for glycemic variability in patients with T2DM, meaning better glycemic control and less glucose fluctuation.