Whether insulin would actually improve athletic performance is unclear, but concerns about its use led the International Olympic Committee to ban use of the hormone by non-diabetic athletes in 1998.The book Game of Shadows (2001), by reporters Mark Fainaru-Wada and Lance Williams, included allegations that baseball player Barry Bonds used insulin (as well as other drugs) in the apparent belief that it would increase the effectiveness of the growth hormone he was alleged to be taking. Bonds eventually testified in front of a federal grand jury as part of a government investigation of BALCO.Bodybuilders in particular are claimed to be using exogenous insulin and other drugs in the belief that they will increase muscle mass. Bodybuilders have been described as injecting up to 10 IU of regular synthetic insulin before eating sugary meals. A 2008 report suggested that insulin is sometimes used in combination with anabolic steroids and growth hormone (GH), and that "Athletes are exposing themselves to potential harm by self‐administering large doses of GH, IGF‐I and insulin". Insulin abuse has been mentioned as a possible factor in the deaths of bodybuilders Ghent Wakefield and Rich Piana.Insulin, human growth hormone (HGH) and insulin-like growth factor 1 (IGF-1) are self-administered by those looking to increase muscle mass beyond the scope offered by anabolic steroids alone. Their rationale is that since insulin and HGH act synergistically to promote growth, and since IGF-1 is a primary mediator of musculoskeletal growth, the stacking of insulin, HGH and IGF-1 should offer a synergistic growth effect on skeletal muscle.
In July 2021, the FDA approved insulin glargine-yfgn (Semglee), a biosimilar product that contains the long acting analog insulin glargine. Insulin glargine-yfgn is interchangeable and less expensive than the reference product, insulin glargine (Lantus), which had been approved in 2000. The FDA requires that new insulin products are non-inferior to existing insulin products with respect to reduction in hemoglobin A1c. See Misbin, RI (February 2022). Insulin - History from an FDA Insider. Politics and Prose Publishing, Washington DC. Text ISBN 978-I-62429-391-7

Research
Inhalation
In 2006 the U.S. Food and Drug Administration (FDA) approved the use of Exubera, the first inhalable insulin. It was withdrawn from the market by its maker as of third quarter 2007, due to lack of acceptance. Inhaled insulin claimed to have similar efficacy to injected insulin, both in terms of controlling glucose levels and blood half-life. Currently, inhaled insulin is short acting and is typically taken before meals; an injection of long-acting insulin at night is often still required. When people were switched from injected to inhaled insulin, no significant difference was observed in HbA1c levels over three months.