According to registered dietitian and certified diabetes educator, Justine Chan, whey protein powder is a good option for people with diabetes as it slows down stomach emptying, stimulates insulin, and reduces blood glucose. Whey isolate protein is the best option, but concentrate and hydrolyzed whey protein are also good choices. Plant-based proteins can be a good option for vegetarians or those with stomach issues, but calorie to protein ratio should still be checked.