The present study will evaluate the efficacy and short-time complications of three types of SPH polymer-based oral insulin capsules on blood glucose in patients with type 1 diabetes. This study is a double blind, multi-stage clinical trial. Fifteen adult patients with type 1 diabetes mellitus are selected from diabetes clinic of Dr. Shariati General Hospital to participate in this study. Exclusion criteria are any previous hypersensitivity to polymer, clinically diagnosed diabetic gastroparesia, forcing patients to use drugs intervention with insulin during study, history of systemic disorders. The trial composes of a screening visit (visit 1) and five trial visits (visit 2-6). Screening includes medical history, physical examination and clinical and laboratory tests within one month prior to enter to the study. Trial visits consist of three types of oral insulin (800 IU/ core inside, 800 IU/core outside and 1600 IU/core outside), a placebo and subcutaneous (SC) administration of 0.1 IU/kg regular insulin. SC regular insulin study is performed on the first trial visit and all patients receive the other four types of capsules (three of oral insulin and a placebo) in randomized order visits. On the first day (SC insulin study) patients receive a meal 30 minutes after insulin injection. On the other four visits (oral insulin or placebo) patients receive the similar meal 180 minutes after ingestion of capsule. There are seven days between two visits as a wash-out period. Patients have not received long acting insulin during last 24 hours. Venous blood samples for determination of plasma glucose and insulin concentrations will collect: At injection visit, 0(immediately before dosing), 5, 15, 30 (immediately before the meal), 60, 90, 120, 180, 240, and 360min; and at oral capsule visit, 0 (immediately before dosing), 30, 60, 120, 150, 180(immediately before the meal), 210, 240, 300, 360 min. The patients are registered under the close supervision with the glucometer BS, vital sign, symptoms of hypoglycemia, and other possible complications during blood sampling and 48 hours after sampling and the existence of any form of symptoms and complications are recorded as being severe symptoms will be excluded from the study.