The Correlation Between Skeletal Muscle Changes Evaluated By MRI And Insulin Resistance And Islet β Cell Function In Type 2 Diabetes Mellitus

Objective: The aim of this study is to measure the changes of skeletal muscle of lower limbs and waist in type 2 diabetes mellitus(T2DM)and healthy subjects using multimodal MRI quantitative techniques,and to analyze the correlation of MRI characteristics of skeletal muscle in different parts of T2 DM and healthy subjects with insulin resistance,islet β-cell function,and other T2 DM related glucose and lipid metabolism indicators.To explore the early warning indicators of MRI characteristics of skeletal muscle in patients with type 2 diabetes mellitus(T2DM)and the potential role of skeletal muscle changes in the whole process of T2 DM.Methods: A total of 17 male patients with T2 DM who were first diagnosed in the Department of Endocrinology of the First Affiliated Hospital of Dalian Medical University from November 2021 to November 2022 were prospectively collected as the experimental group,with an average age of 50.00±11.31 years.At the same time,17age-matched healthy male volunteers living in the same city were selected as the control group,with an average age of 44.65±10.97 years.The general information of the two groups of subjects was recorded.Laboratory tests included fasting blood glucose(FBG),glycosylated hemoglobin(Hb Alc),fasting C-peptide,total cholesterol(TC),triglyceride(TG),low-density lipoprotein(LDL),and high-density lipoprotein(HDL).Insulin resistance index(HOMA-IR)and Insulin secretion(HOMA-β)was calculated.Each subject underwent MRI examination within 2 weeks from the date of venous blood collection.The lower limbs and waist skeletal muscle were scanned with a Philips Ingenia CX 3.0T MR Scanner.The images were processed using Philips post-processing workstation,and the content of intermuscular adipose tissue(IMAT)and intramuscular fat(intra MF)in the legs and waist,and the FA and ADC values of skeletal muscle fibers were obtained.ROC curve was used to analyze the cut-off value and diagnostic efficacy of the above values in the diagnosis of T2 DM.Independent sample t test and Person correlation analysis were used to complete the statistics and analysis.Results:(1)There were significant differences in the IMAT value of the left leg,the fat fraction(FF)of psoas major,the FF of quadratus lumborum,the FF of autochthonous back muscles and the mean FF of lumbar muscles between the experimental group and the control group(P<0.05),while there were no significant differences in the other skeletal muscle MRI parameters between the two groups(P>0.05).(2)The ROC curve for the diagnosis of T2 DM showed that there were a sensitivity of 82.4% and a specificity of 81.2% with the proportion of 8.995% as the cut-off value for the left leg IMAT.The sensitivity and specificity of T2 DM diagnosis were 64.7% and 81.2% when FF of psoas major was 4.835% as the cut-off value.With 3.010 as the cut-off value of FF,the sensitivity and specificity of T2 DM diagnosis were 88.2% and 62.5%,respectively.There were a sensitivity of 64.7% and a specificity of 87.5% for the diagnosis of T2 DM with a cut-off value of 12.49 for the FF of autochthonous back muscles.There were a sensitivity of 70.6% and a specificity of 81.2% for T2 DM with a cut-off value of 7.025 for the mean FF of lumbar muscles.The area under the curve(AUC)of IMAT of left leg,FF of psoas major,FF of quadratus lumborum,FF of autochthonous back muscles and mean FF of lumbar muscles for T2 DM diagnosis were0.842,0.765,0.750,0.765 and 0.776,respectively.(3)IMAT of left leg,FF of psoas major,FF of quadratus lumborum,FF of autochthonous back muscles and mean FF of lumbar skeletal muscle were correlated with fasting blood glucose.The FF of psoas major muscle is correlated with Hba1 c.IMAT of left leg,FF of quadratus lumborum,FF of autochthonous back muscles and mean FF of lumbar muscles were correlated with HOMA-IR.The FF of psoas major,autochthonous back muscles and mean FF of lumbar muscles were correlated with HOMA-β.IMAT of left leg,FF of psoas major muscle,FF of quadratus lumborum and mean FF of lumbar muscles were correlated with high-density lipoprotein.Conclusions: The content of intra MF in lumbar skeletal muscle and IMAT in left leg is correlated with insulin resistance in male patients with newly diagnosed T2 DM.m Dixon-Quant sequence has potential value in evaluating skeletal muscle changes and predicting β cell function.