Objective：To explore the relationship between body mass index（BMI）and different metabolic variables（glucose and lipid metabolism，hepatic，renal and thyroid function）in newly diagnosed type 2 diabetes mellitus patients with normal serum TSH. Methods：We retrospectively collected clinical data from 156 newly diagnosed type 2 diabetes mellitus patients with normal serum TSH in our center，including gender，age，BMI，alanine aminotransferase（ALT），γ-glutamyltransferase（γ-GT），blood urea nitrogen（BUN），creatinine（Cr），uric acid（UA），fasting plasma glucose（FPG），fasting C-peptide（CP），fasting insulin（FINS），glycosylated hemoglobin A1c（HbA1c），insulin resistance（HOMA-IR），triglyceride（TG），total cholesterol（TC），low-density lipoprotein cholesterol（LDL-C），high-density lipoprotein cholesterol（HDL-C），free triiodothyronine（FT3），free thyroxin（FT4），thyroid stimulating hormone（TSH）. All the patients were divided into the obesity group（BMI ≥28.0 kg/m2），the overweight group（24.0 kg/m2≤BMI＜28.0 kg/m2）and the normal weight group（BMI＜24.0 kg/m2）according to BMI. The differences of metabolic variables among three groups and the correlation between BMI and different metabolic variables were analyzed. Results：Levels of ALT，γ-GT，TC，FINS，HOMA-IR，CP and TSH among groups were significantly different（P < 0.05）. After adjustment for gender，age and HBA1c，levels of ALT，γ-GT，FINS，HOMA-IR，CP and TSH increased with the increase of BMI（r=0.22，0.19，0.36，0.38，0.27，0.22，P < 0.05）. Conclusion：BMI could significantly affect ALT，γ-GT，TC，FINS，HOMA-IR，CP and TSH in newly diagnosed type 2 diabetes mellitus patients with normal serum TSH. Besides，ALT，γ-GT，FINS，HOMA-IR，CP and TSH were positively correlated with BMI. TSH level could serve as an index in evaluating metabolic disorder and follow-up in newly diagnosed type 2 diabetes mellitus，especially with obesity.