Eli Lilly CEO David Ricks said Tuesday that Sen. Elizabeth Warren's accusation that the drugmaker failed on its pledge to provide patients with lower-priced insulin is "nonsense."

Warren, among the frontrunners in the 2020 presidential race, released a survey Monday, which looked at 190 chains and 196 independent pharmacies across all 50 states. The results found that 83% of pharmacies surveyed did not have Lispro, Eli Lilly's rebranded cheaper insulin, in stock or available to customers. In some cases, the pharmacists did not inform customers that a cheaper version was available.

"This report shows that pharmaceutical giant Eli Lilly has not lived up to its promise to provide a lower-priced insulin to patients who need it," Warren said in a statement.

Ricks shot back on "Mad Money" on Tuesday, telling CNBC's Jim Cramer that the company's half-priced insulin is "a pretty big difference" to consumers and is "widely" available.