Supplementary Material for: Cardiovascular risk factors in children and adolescents with type 1 diabetes mellitus: the role of insulin resistance and associated genetic variants

Introduction: Type 1 diabetes (T1D) is associated with increased risk of cardiovascular disease. Insulin resistance is an important cardiovascular risk factor (CVRF), also in subjects with T1D, but the influence of the genetic predisposition of insulin resistance on cardiovascular risk is still unknown in T1D. We aimed to determine whether a genetic score composed of six variants, previously associated to insulin resistance and type 2 diabetes (T2D) risk, associates with insulin sensitivity and known CVRFs in children and adolescents with T1D. Materials and Methods: 330 children and adolescents (174 males; mean age 15.7±3.5 years) with T1D were genotyped for the following genetic variants: rs1801278 (IRS1), rs1044498 (ENPP1), rs2295490 (TRIB3), rs1801282 (PPARG), rs780094 (GCKR), and rs35767 (IGF1). An additive genetic risk score (GRS) and cardiovascular risk score (CVRS) were calculated. Anthropometric, glycemic control, insulin sensitivity, blood pressure, and biochemical parameters were assessed. Multivariate regression between evaluated phenotypes and GRS were performed. Results: We found a significant association between the GRS and estimated insulin sensitivity [β=-0.027 (-0.040 to -0.013), R2=0.86, p=<0.001], diastolic blood pressure [β=0.68 (0.08-1.27), R2=0.20, p=0.026], triglycerides [β=4.26 (1.74-6.77), R2=0.13, p=0.001], waist to height ratio [β=0.003 (0.001-0.006), R2=0.75, p=0.010], non-HDL-cholesterol [β=3.63 (1.39-5.87), R2=0.12, p=0.002], and CVRS [β=0.063 (0.008-0.118), R2=0.19, p=0.025], independent of age, sex, BMI, pubertal stage, diabetes duration, HbA1c, type of treatment and total insulin requirement. The addition of the GRS to established clinical risk factors significantly improved the discriminatory capability of the regression model for predicting subjects with more CVRFs (C-statistic 0.89 [95%CI 0.84–0.95] vs. 0.83 [0.73–0.93]; p = 0.037). Conclusions: Insulin resistance and T2D risk-associated genetic variants influence insulin sensitivity and known cardiovascular risk factors in children and adolescents with T1D.

引言：1型糖尿病（Type 1 diabetes, T1D）与心血管疾病风险升高密切相关。胰岛素抵抗是重要的心血管危险因素（cardiovascular risk factor, CVRF），在1型糖尿病患者群体中亦不例外，但胰岛素抵抗的遗传易感性对1型糖尿病患者心血管风险的具体影响目前仍未明确。本研究旨在探讨一种由6种既往被证实与胰岛素抵抗及2型糖尿病（Type 2 diabetes, T2D）风险相关的遗传变异构成的遗传评分，是否与1型糖尿病儿童及青少年的胰岛素敏感性及已知心血管危险因素存在关联。

材料与方法：本研究对330例1型糖尿病儿童及青少年（174例男性，平均年龄15.7±3.5岁）进行了以下遗传变异的基因分型：rs1801278（IRS1）、rs1044498（ENPP1）、rs2295490（TRIB3）、rs1801282（PPARG）、rs780094（GCKR）及rs35767（IGF1）。同时计算了加性遗传风险评分（genetic risk score, GRS）与心血管风险评分（cardiovascular risk score, CVRS）。对所有受试者的人体测量学指标、血糖控制情况、胰岛素敏感性、血压及生化参数进行了系统评估，并开展了评估表型与GRS之间的多元回归分析。

结果：在校正年龄、性别、体重指数、青春期分期、糖尿病病程、糖化血红蛋白、治疗方案及总胰岛素需求量等混杂因素后，本研究发现遗传风险评分与以下指标存在显著关联：估算胰岛素敏感性[β=-0.027（-0.040~-0.013），R²=0.86，p<0.001]、舒张压[β=0.68（0.08~1.27），R²=0.20，p=0.026]、甘油三酯[β=4.26（1.74~6.77），R²=0.13，p=0.001]、腰围身高比[β=0.003（0.001~0.006），R²=0.75，p=0.010]、非高密度脂蛋白胆固醇[β=3.63（1.39~5.87），R²=0.12，p=0.002]及心血管风险评分[β=0.063（0.008~0.118），R²=0.19，p=0.025]。将遗传风险评分加入已确立的临床危险因素模型后，用于预测合并更多心血管危险因素受试者的回归模型判别能力得到显著提升（C统计量：0.89[95%CI 0.84~0.95] vs 0.83[0.73~0.93]；p=0.037）。

结论：与胰岛素抵抗及2型糖尿病风险相关的遗传变异，可对1型糖尿病儿童及青少年的胰岛素敏感性与已知心血管危险因素产生影响。