Oats are cheap, and oatmeals might improve your immune system and insulin sensitivity. 

Researchers in Chicago carried out a randomized, double-blind, controlled clinical trial of 97 men and women, in which half of the group consumed foods containing oat beta-glucan, while the other half ate control foods. The oat group showed improvements in insulin sensitivity, while the control group was unchanged. (European Journal of Clinical Nutrition, June 2007)

Researchers in Mannheim, Germany carried out a dietary intervention with 14 patients who had uncontrolled type 2 diabetes and insulin resistance. The patients were introduced to a diabetes-appropriate diet containing oatmeal during a short hospital stay, then examined again four weeks later. On average, patients achieved a 40% reduction in insulin dosage – and maintained the reduction even after 4 weeks on their own at home. (Experimental and Clinical Endocrinology & Diabetes, February 2008)