Type 2 diabetes was associated with significantly increased iNOS levels in skeletal muscle compared to healthy controls (34.3 vs 8.5 ng/mg protein; P<0.00002), alongside elevated inflammatory markers.
Case-Control (n=26)
Type 2 diabetes is associated with increased inflammation and iNOS induction in skeletal muscle, which may contribute to muscle damage and insulin resistance.
Absolute Event Rate: 34.3% vs 8.5%
p-value: p=<0.00002
An inflammatory process may be involved in nitric oxide production in skeletal muscle of type 2 diabetic patients. Nitric oxide generation in skeletal muscle was assessed in 14 non-complicated type 2 diabetic patients and in 12 healthy subjects. In samples of quadriceps femoris muscle, endothelial nitric oxide synthase (eNOS), inducible nitric oxide synthase (iNOS), nitrite, nitrate and nitrotyrosine were determined. The macrophage-specific antigen CD163, the T-cell membrane factor CD154 and tumour necrosis factor-alpha (TNF-alpha) were also assayed. In six patients, ultrastructural analysis of muscle was performed. Nitrites and nitrates were increased in patients as compared to controls (22.7+/-4.5 and 32.7+/-7.0 vs 16.0+/-2.9 and 22.8+/-4.0 micromol/mg protein; P<0.001, Mann-Whitney U test). Endothelial NOS was similar in diabetic and control subjects (36.4+/-13.8 vs 36.3+/-6.8 ng/mg protein), contrasting with the significant increase of iNOS recorded in patients (34.3+/-13.0 vs 8.5+/-2.8 ng/mg protein, P<0.00002). Nitrotyrosine levels were higher in the patient than in the control group (42.1+/-24.4 vs 10.3+/-2.5 ng/mg protein, P<0.00002), as were CD163 (10-fold) and TNF-alpha (fourfold) levels. Furthermore, CD154 levels were detectable only in the patient samples (10.2+/-5.3 ng/mg protein). By multiple-regression analysis, changes in glycated haemoglobin values could predict 96% variation in nitrotyrosine. Macrophages were present in all muscle samples analysed by electromicroscopy. The increased levels of CD163, CD154 and TNF-alpha indicate that an inflammatory process occurs in skeletal muscle of type 2 diabetic patients. This may contribute to iNOS induction, muscle damage and insulin resistance.
Torres et al. (2004) conducted a case-control in Type 2 diabetes (n=26). Type 2 diabetes vs. Healthy subjects was evaluated on Inducible nitric oxide synthase (iNOS) levels in skeletal muscle (ng/mg protein) (p=<0.00002). Type 2 diabetes was associated with significantly increased iNOS levels in skeletal muscle compared to healthy controls (34.3 vs 8.5 ng/mg protein; P<0.00002), alongside elevated inflammatory markers.