Achieving the composite endpoint of glycated haemoglobin <7.0%, no weight gain and no hypoglycaemia in the once-weekly dulaglutide AWARD programme.

AIM: To compare the effectiveness of dulaglutide 1.5 and 0.75 mg with active comparators and placebo with regard to a composite endpoint of glycated haemoglobin (HbA1c), weight and hypoglycaemia, using post hoc analyses. METHODS: A logistic regression analysis was performed on the intention-to-treat population, using data from the last observation carried forward, and the composite endpoint of HbA1c <7.0% (53 mmol/mol), no weight gain (≤0 kg) and no hypoglycaemia (glucose <3.0 mmol/l or severe hypoglycaemia) after 26 weeks for each trial in the AWARD programme separately. RESULTS: At 26 weeks, within each study, 37-58% of patients on dulaglutide 1.5 mg, 27-49% of patients on dulaglutide 0.75 mg, and 9-61% of patients on active comparators achieved the composite endpoint. Significantly more patients reached the composite endpoint with dulaglutide 1.5 mg than with metformin, sitagliptin, exenatide twice daily or insulin glargine: odds ratio (OR) 1.5 [95% confidence interval (CI) 1.0, 2.2; p < 0.05], OR 4.5 (95% CI 3.0, 6.6; p < 0.001), OR 2.6 (95% CI 1.8, 3.7; p < 0.001) and OR 7.4 (95% CI 4.4, 12.6; p < 0.001), respectively, with no difference between dulaglutide 1.5 mg and liraglutide 1.8 mg. In addition, significantly more patients reached the composite endpoint with dulaglutide 0.75 mg than with sitagliptin or insulin glargine: OR 3.3 (95% CI 2.2, 4.8; p < 0.001) and OR 4.5 (95% CI 2.7, 7.8; p < 0.001), respectively. CONCLUSIONS: Dulaglutide is an effective treatment option, resulting in a similar or greater proportion of patients reaching the HbA1c target of <7.0% (53 mmol/mol), without weight gain or hypoglycaemia compared with active comparators.

Fat-induced membrane cholesterol accrual provokes cortical filamentous actin destabilisation and glucose transport dysfunction in skeletal muscle.

AIMS/HYPOTHESIS: Diminished cortical filamentous actin (F-actin) has been implicated in skeletal muscle insulin resistance, yet the mechanism(s) is unknown. Here we tested the hypothesis that changes in membrane cholesterol could be a causative factor, as organised F-actin structure emanates from cholesterol-enriched raft microdomains at the plasma membrane. METHODS: Skeletal muscle samples from high-fat-fed animals and insulin-sensitive and insulin-resistant human participants were evaluated. The study also used L6 myotubes to directly determine the impact of fatty acids (FAs) on membrane/cytoskeletal variables and insulin action. RESULTS: High-fat-fed insulin-resistant animals displayed elevated levels of membrane cholesterol and reduced F-actin structure compared with normal chow-fed animals. Moreover, human muscle biopsies revealed an inverse correlation between membrane cholesterol and whole-body glucose disposal. Palmitate-induced insulin-resistant myotubes displayed membrane cholesterol accrual and F-actin loss. Cholesterol lowering protected against the palmitate-induced defects, whereas characteristically measured defects in insulin signalling were not corrected. Conversely, cholesterol loading of L6 myotube membranes provoked a palmitate-like cytoskeletal/GLUT4 derangement. Mechanistically, we observed a palmitate-induced increase in O-linked glycosylation, an end-product of the hexosamine biosynthesis pathway (HBP). Consistent with HBP activity affecting the transcription of various genes, we observed an increase in Hmgcr, a gene that encodes 3-hydroxy-3-methyl-glutaryl coenzyme A reductase, the rate-limiting enzyme in cholesterol synthesis. In line with increased HBP activity transcriptionally provoking a membrane cholesterol-based insulin-resistant state, HBP inhibition attenuated Hmgcr expression and prevented membrane cholesterol accrual, F-actin loss and GLUT4/glucose transport dysfunction. CONCLUSIONS/INTERPRETATION: Our results suggest a novel cholesterolgenic-based mechanism of FA-induced membrane/cytoskeletal disorder and insulin resistance.