The aim of the study was to compare the efficacy and safety of liraglutide in type 2 diabetes mellitus vs placebo and insulin glargine (A21Gly,B31Arg,B32Arg human insulin), all in combination with metformin and glimepiride. This randomised (using a telephone or web-based randomisation system), parallel-group, controlled 26 week trial of 581 patients with type 2 diabetes mellitus on prior monotherapy (HbA_1c 7.5–10%) and combination therapy (7.0–10%) was conducted in 107 centres in 17 countries. The primary endpoint was HbA_1c. Patients were randomised (2:1:2) to liraglutide 1.8 mg once daily (n = 232), liraglutide placebo (n = 115) and open-label insulin glargine (n = 234), all in combination with metformin (1 g twice daily) and glimepiride (4 mg once daily). Investigators, participants and study monitors were blinded to the treatment status of the liraglutide and placebo groups at all times. The number of patients analysed as intention to treat were: liraglutide n = 230, placebo n = 114, insulin glargine n = 232. Liraglutide reduced HbA_1c significantly vs glargine (1.33% vs 1.09%; −0.24% difference, 95% CI 0.08, 0.39; p = 0.0015) and placebo (−1.09% difference, 95% CI 0.90, 1.28; p < 0.0001). There was greater weight loss with liraglutide vs placebo (treatment difference –1.39 kg, 95% CI 2.10, 0.69; p = 0.0001), and vs glargine (treatment difference −3.43 kg, 95% CI 4.00, 2.86; p < 0.0001). Liraglutide reduced systolic BP (−4.0 mmHg) vs glargine (+0.5 mmHg; −4.5 mmHg difference, 95% CI 6.8, −2.2; p = 0.0001) but not vs placebo (p = 0.0791). Rates of hypoglycaemic episodes (major, minor and symptoms only, respectively) were 0.06, 1.2 and 1.0 events/patient/year, respectively, in the liraglutide group (vs 0, 1.3, 1.8 and 0, 1.0, 0.5 with glargine and placebo, respectively). A slightly higher number of adverse events (including nausea at 14%) were reported with liraglutide, but only 9.8% of participants in the group receiving liraglutide developed anti-liraglutide antibodies. Liraglutide added to metformin and sulfonylurea produced significant improvement in glycaemic control and bodyweight compared with placebo and insulin glargine. The difference vs insulin glargine in HbA_1c was within the predefined non-inferiority margin.

The concept of diabetic retinopathy as a microvascular disease has evolved, in that it is now considered a more complex diabetic complication in which neurodegeneration plays a significant role. In this article we provide a critical overview of the role of microvascular abnormalities and neurodegeneration in the pathogenesis of diabetic retinopathy. A special emphasis is placed on the pathophysiology of the neurovascular unit (NVU), including the contributions of microvascular and neural elements. The potential mechanisms linking retinal neurodegeneration and early microvascular impairment, and the effects of neuroprotective drugs are summarised. Additionally, we discuss how the assessment of retinal neurodegeneration could be an important index of cognitive status, thus helping to identify individuals at risk of dementia, which will impact on current procedures for diabetes management. We conclude that glial, neural and microvascular dysfunction are interdependent and essential for the development of diabetic retinopathy. Despite this intricate relationship, retinal neurodegeneration is a critical endpoint and neuroprotection, itself, can be considered a therapeutic target, independently of its potential impact on microvascular disease. In addition, interventional studies targeting pathogenic pathways that impact the NVU are needed. Findings from these studies will be crucial, not only for increasing our understanding of diabetic retinopathy, but also to help to implement a timely and efficient personalised medicine approach for treating this diabetic complication.