Objective To explore the correlation between the ratio of free triiodothyronine/free thyroxine(FT3/FT4)and the early-phase insulin secretion index(ΔI30/ΔG30)in type 2 diabetes mellitus(T2DM)patients with normal thyroid function.Methods 200 patients with T2DM with normal thyroid function in Hebei General Hospital from September 2019 to June 2021 were selected and divided into the Q1 group with FT3/FT4≤0.26(n=67),the Q2 group with 0.27≤FT3/FT4≤0.29(n=67),and the Q3 group with FT3/FT4≥0.30(n=66)according to the tertiles of the FT3/FT4.The general data,biochemical indicators and islet functions of the three groups were compared,and the relationship between the FT3/FT4 ratio and the ΔI30/ΔG30 as well as the islet β cell function was analyzed.Results The fasting insulin(FIns),2 h postprandial insulin(2 hIns),homeostatic model assessment of islet β cell(HOMA-β)and area under the curve of insulin(AUCI)in Q3 group were higher than those in Q1 and Q2 groups(P<0.05),2 h postprandial blood glucose(2 hPG)in Q3 group was lower than those in Q1 and Q2 groups(P<0.05).Systolic blood pressure in Q2 group was higher than those in Q1 group(P<0.05).Compared with Q1 group,diastolic blood pressure,body mass index(BMI),alanine aminotransferase(ALT),fasting C-peptide(FC-P),area under curve of C-P(AUCC),2 h postprandial C-peptide(2 hC-P)and ΔI30/ΔG30 in Q3 group were significantly higher(P<0.05),and HbA1c was significantly lower(P<0.05).Spearman correlation analysis showed that Δ I30/Δ G30,HOMA-β,AUCI,AUCC and HOMA-IR were positively correlated with BMI,ALT,FC-P,2 hC-P,FIns,2 hIns and FT3/FT4(P<0.05),it was negatively correlated with HbA1c and 2 hPG(P<0.05).Linear regression analysis showed that ΔI30/ΔG30,HOMA-β,AUCI and AUCC were the influencing factors of FT3/FT4 after adjusting for confounding factors.Conclusions ΔI30/ΔG30,HOMA-β,AUCI and AUCC are the influencing factors of FT3/FT4 in T2DM patients with normal thyroid function,suggesting that FT3/FT4 is higher in patients with better islet β cell secretion function.

Objective To explore the correlation between the ratio of free triiodothyronine/free thyroxine(FT3/FT4)and the early-phase insulin secretion index(ΔI30/ΔG30)in type 2 diabetes mellitus(T2DM)patients with normal thyroid function.Methods 200 patients with T2DM with normal thyroid function in Hebei General Hospital from September 2019 to June 2021 were selected and divided into the Q1 group with FT3/FT4≤0.26(n=67),the Q2 group with 0.27≤FT3/FT4≤0.29(n=67),and the Q3 group with FT3/FT4≥0.30(n=66)according to the tertiles of the FT3/FT4.The general data,biochemical indicators and islet functions of the three groups were compared,and the relationship between the FT3/FT4 ratio and the ΔI30/ΔG30 as well as the islet β cell function was analyzed.Results The fasting insulin(FIns),2 h postprandial insulin(2 hIns),homeostatic model assessment of islet β cell(HOMA-β)and area under the curve of insulin(AUCI)in Q3 group were higher than those in Q1 and Q2 groups(P<0.05),2 h postprandial blood glucose(2 hPG)in Q3 group was lower than those in Q1 and Q2 groups(P<0.05).Systolic blood pressure in Q2 group was higher than those in Q1 group(P<0.05).Compared with Q1 group,diastolic blood pressure,body mass index(BMI),alanine aminotransferase(ALT),fasting C-peptide(FC-P),area under curve of C-P(AUCC),2 h postprandial C-peptide(2 hC-P)and ΔI30/ΔG30 in Q3 group were significantly higher(P<0.05),and HbA1c was significantly lower(P<0.05).Spearman correlation analysis showed that Δ I30/Δ G30,HOMA-β,AUCI,AUCC and HOMA-IR were positively correlated with BMI,ALT,FC-P,2 hC-P,FIns,2 hIns and FT3/FT4(P<0.05),it was negatively correlated with HbA1c and 2 hPG(P<0.05).Linear regression analysis showed that ΔI30/ΔG30,HOMA-β,AUCI and AUCC were the influencing factors of FT3/FT4 after adjusting for confounding factors.Conclusions ΔI30/ΔG30,HOMA-β,AUCI and AUCC are the influencing factors of FT3/FT4 in T2DM patients with normal thyroid function,suggesting that FT3/FT4 is higher in patients with better islet β cell secretion function.