Sucharita S, Pranathi R, Correa M, Keerthana P, Ramesh L J, Bantwal G, Venkatappa H M, Mahadev K P, Thomas T, Bosch R J, Harridge S D R, Kurpad A V
Department of Physiology, Pathology, Biostatistics, Orthopaedics and Endocrinology, St John's Medical College and Hospital, Bangalore, Karnataka, India.
School of Information Sciences, Manipal Academy of Higher Education, Manipal, India.
Eur J Clin Nutr. 2019 Oct;73(10):1373-1381. doi: 10.1038/s41430-019-0402-4. Epub 2019 Feb 6.
The rise in prevalence rates of Type 2 Diabetes among Indians is well recognized. The research focus has been primarily to understand the changes in insulin sensitivity and beta cell dysfunction among Indians with Type 2 Diabetes. However, no data are available on the role of peripheral tissue, in particular intramyocellular lipid (IMCL) content and its impact on glucose homeostasis among Indians with prediabetes.
28 male subjects (20-40 year) were studied. 13 with prediabetes (BMI ranging from 25.4 ± 2.9 kg/m) and 15 controls (BMI ranging from 24.6 ± 2.8 kg/m) were recruited. Body composition by dual energy X-ray absorptiometry (DXA), insulin sensitivity, insulin secretion rates were derived using the minimal model of C-peptide secretion and kinetics rates and skeletal muscle strength of the lower limb (quadriceps) was assessed using Isokinetic dynamometry. From muscle biopsy samples of the vastus lateralis, IMCL fat content (Oil red O staining) was determined.
The prediabetes group were older compared to controls (P < 0.01), but had similar BMI. The muscle to fat ratio, plasma Insulin, C peptide, HOMA-IR and HOMA % B were also comparable between the groups. IMCL fat content (%) was significantly higher in the prediabetes group compared to controls (7.0 ± 0.7% vs. 2.0 ± 0.3%, P < 0.01). This difference persisted even after controlling for age. Overall the IMCL fat content (%) was positively and significantly associated with HbA1c (r = 0.76, P < 0.01). HOMA-IR was significantly correlated with central (android, trunk) adiposity (kg) (r = 0.71, P < 0.01) but not with IMCL (%).
This is the first direct evidence of existence of significantly higher lipid levels within skeletal muscle cells among normal and overweight young Indians with prediabetes. However, there was no association between IMCL and HOMA-IR among the prediabetes group.
印度2型糖尿病患病率的上升已得到广泛认可。研究重点主要是了解印度2型糖尿病患者胰岛素敏感性和β细胞功能障碍的变化。然而，关于外周组织，特别是肌内脂质（IMCL）含量在糖尿病前期印度人中的作用及其对葡萄糖稳态的影响，尚无相关数据。
对28名男性受试者（20 - 40岁）进行研究。招募了13名糖尿病前期患者（BMI范围为25.4±2.9kg/m）和15名对照者（BMI范围为24.6±2.8kg/m）。通过双能X线吸收法（DXA）测量身体成分，使用C肽分泌和动力学速率的最小模型推导胰岛素敏感性、胰岛素分泌率，并使用等速测力法评估下肢（股四头肌）的骨骼肌力量。从外侧股四头肌的肌肉活检样本中测定IMCL脂肪含量（油红O染色）。
糖尿病前期组比对照组年龄更大（P < 0.01），但BMI相似。两组之间的肌肉与脂肪比例、血浆胰岛素、C肽、HOMA-IR和HOMA%B也相当。糖尿病前期组的IMCL脂肪含量（%）显著高于对照组（7.0±0.7%对2.0±0.3%，P < 0.01）。即使在控制年龄后，这种差异仍然存在。总体而言，IMCL脂肪含量（%）与糖化血红蛋白（HbA1c）呈显著正相关（r = 0.76，P < 0.01）。HOMA-IR与中心性（男性型、躯干）肥胖（kg）显著相关（r = 0.71，P < 0.01），但与IMCL（%）无关。
这是首次直接证明在患有糖尿病前期的正常和超重年轻印度人的骨骼肌细胞内存在显著更高的脂质水平。然而，在糖尿病前期组中，IMCL与HOMA-IR之间没有关联。
