Abstract: The present invention provides a method for achieving a therapeutically effective plasma levels of insulin by administering at least two doses of pharmaceutical formulation of insulin sequentially into the same nostril. The administration of the second dose in the same nostril gives substantially higher plasma levels of insulin when compared with sequential administration in two different nostrils. Without being limited to any specific physiological mechanism, it is believed that the first dose of insulin acts as a loading dose. This loading dose is required to achieve the subsequent plasma levels of insulin that are observed with subsequent doses. The Cmax of plasma insulin achieved by the methods and formulations of the present invention is at least about 70 microU/ml when plasma insulin is measured from about 0 to about 45 minutes after administration of a second dose. The AUC achieved is at least about 1800 microU/(ml*min).