Vitamin B₁₂ as a carrier for the oral delivery of insulin

The noninvasive delivery of insulin continues to be a major goal for the treatment of diabetes mellitus. Oral-enteric administration would make insulin delivery easier and more effective, as higher patient compliance and improved glycemic control are likely; yet the oral-enteric pathway has been unfeasible owing to insulin's susceptibility to proteolytic degradation and inefficient enteric uptake. Herein we show that a noninvasive oral delivery route for insulin is possible through the vitamin B₁₂ uptake pathway. In diabetic rat models, insulin-B₁₂ conjugates can significantly lower blood glucose levels when administered orally.