Insulin Therapy in Type 2 Diabetes.

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Since the discovery of insulin, it was the only drug available for the treatment of diabetes until the development of sulfonylureas and biguanides 50 years later. But even with the availability of oral glucose-lowering drugs, insulin supplementation was often needed to achieve good glucose control in type 2 diabetes. Insulin NPH became the basal insulin therapy of choice and adding NPH to metformin and/or sulfonylureas became the standard of care until basal insulin analogs were developed and new glucose-lowering drugs became available. The advantages in cost-benefit of insulin analogs and their combination with new glucose-lowering drugs are still a matter of debate. There is no general agreement on how to avoid inertia by prescribing insulin therapy in type 2 diabetes when really needed, as reflected by the diversity of recommendations in the current clinical practice guidelines. When necessary for this review, a systematic search of the evidence was done in PubMed and Cochrane databases. Adding new oral glucose-lowering drugs to insulin such as DPP-4 inhibitors lead to a modest HbA1c reduction without weight gain and no increase in hypoglycemia. When SGLT-2 inhibitors are added instead, there is a slightly higher HbA1c reduction, but with body weight and blood pressure reduction. The downside is the increase in genital tract infections. GLP-1 receptor agonists have become the best alternative when basal insulin fails, particularly using fixed ratio combinations. Rapid-acting insulins via the inhaled route may also become an alternative for insulin supplementation and/or intensification. "Smart insulins" are under investigation and may become available for clinical use in the near future. Aggressive weight loss strategies together with the new glucose-lowering drugs which do not cause hypoglycemia nor weight gain should limit the number of patients with type 2 diabetes needing insulin. Nevertheless, because of therapeutic inertia and the progressive nature of the disease, many need at least a basal insulin supplementation and insulin analogs are the best choice as they become more affordable. Fixed ratio combinations with GLP1 receptor agonists are a good choice for intensification of insulin therapy.