Pharmaceutical compositions for nasal administration to humans, or to warm-blooded animals, comprise: (A) a therapeutically effective amount of insulin; (B) a permeation enhancer; and (C) a liquid carrier; the compositions being further comprised of, or characterized by, any, or each, of: (D) a combination of non-ionic surfactants; wherein the combination of non-ionic surfactants comprises: (i) at least one fatty acid ester of a sugar or sugar alcohol and (ii) at least one pegylated fatty acid ester of a sugar or sugar alcohol; (E) an acidic pH, but no greater than a pH of 4.5; and (F) an osmolality of