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Abstract Background Insulin resistance (IR) in skeletal muscle is a key feature of the pre-diabetic state, hypertension, dyslipidemia, cardiovascular diseases and also predicts type 2 diabetes. However, the underlying molecular mechanisms are still poorly understood. Methods To explore these mechanisms, we related global skeletal muscle gene expression profiling of 38 non-diabetic men to a surrogate measure of insulin sensitivity, i.e. homeostatic model assessment of insulin resistance (HOMA-IR). Results We identified 70 genes positively and 110 genes inversely correlated with insulin sensitivity in human skeletal muscle, identifying autophagy-related genes as positively correlated with insulin sensitivity. Replication in an independent study of 9 non-diabetic men resulted in 10 overlapping genes that strongly correlated with insulin sensitivity, including SIRT2, involved in lipid metabolism, and FBXW5 that regulates mammalian target-of-rapamycin (mTOR) and autophagy. The expressions of SIRT2 and FBXW5 were also positively correlated with the expression of key genes promoting the phenotype of an insulin sensitive myocyte e.g. PPARGC1A. Conclusions The muscle expression of 180 genes were correlated with insulin sensitivity. These data suggest that activation of genes involved in lipid metabolism, e.g. SIRT2, and genes regulating autophagy and mTOR signaling, e.g. FBXW5, are associated with increased insulin sensitivity in human skeletal muscle, reflecting a highly flexible nutrient sensing.

Abstract Background Hypoglycaemia, especially nocturnal, remains the main limiting factor of achieving good glycaemic control in type 1 diabetes. The effect of first generation long-acting insulin analogues in reducing nocturnal hypoglycaemia is well documented in patient with type 1 diabetes. The effect of the newer long-acting insulin degludec on risk of nocturnal hypoglycaemia remains undocumented in patients with type 1 diabetes and recurrent severe nocturnal hypoglycaemia. The HypoDeg trial is designed to investigate whether insulin degludec in comparison with insulin glargine U100 is superior in limiting the occurrence of nocturnal hypoglycaemia in patients with recurrent nocturnal severe hypoglycaemia. This paper reports the study design of the HypoDeg trial. Methods/design A Danish investigator-initiated, prospective, randomised, open, blinded endpoint (PROBE), multicentre, two-year cross-over study investigating the effect of insulin degludec versus insulin glargine U100 on frequency of nocturnal hypoglycaemia in patients with type 1 diabetes and one or more episodes of nocturnal severe hypoglycaemia during the preceding two years as the major inclusion criteria. Patients are randomised (1:1) to basal therapy with insulin degludec or insulin glargine. Insulin aspart is used as bolus therapy in both treatment arms. Discussion In contrast to most other insulin studies the HypoDeg trial includes only patients at high risk of hypoglycaemia. The HypoDeg trial will compare treatment with insulin degludec to insulin glargine U100 in terms of risk of nocturnal hypoglycaemic episodes in patients with type 1 diabetes with the greatest potential to benefit from near-physiological insulin replacement therapy. www.clinicaltrials.gov: NCT02192450.