Improved glycemic control is associated with a reduced risk of diabetic complications. Optimal management of patients with type 2 diabetes includes nutritional therapy, physical activity, and pharmacotherapy for glycemic control. Most patients with type 2 diabetes are initially managed with oral antidiabetic agents, but as β-cell function declines and the disease progresses, insulin therapy is frequently needed to maintain glycemic control. Insulin therapy given with multidose insulin injection regimen or by continuous insulin infusion is needed for patients with type 1 diabetes to achieve control. Obesity and its associated insulin resistance contribute to greater insulin requirements in patients with both type 1 and type 2 diabetes to achieve glycemic control, creating a need for concentrated insulin. Concentrated insulin formulations can be prescribed as an alternative to 100 unit/mL insulin and provide the advantage of low injection volume, leading to less pain and possibly fewer insulin injections. This review includes a stepwise analysis of all currently available concentrated insulin products, analyzes the most up-to-date evidence, and presents this in combination with expert guidance and commentary in an effort to provide clinicians with a thorough overview of the characteristics and benefits of concentrated insulins in patients with type 1 and type 2 diabetes- instilling confidence when recommending, prescribing, and adjusting these medications.