If you read the drug label on your oral diabetes medication or the accompanying instructions, chances are it will say the prescription medication is best taken with water. There are two good reasons to drink water with blood-glucose medications (and many other meds, too). One is purely mechanical: Drinking about six ounces of water when swallowing a diabetes pill ensures that the pill doesn't lodge in your esophagus, where it can cause irritation or even trigger painful spasms.
The other reason to drink water with your diabetes medication is effectiveness: Medicine isn't absorbed in the esophagus or stomach—it has to make it to the small intestine (that's why so many pills are now coated, to protect them from breaking down too high in the gastrointestinal tract). So a properly "washed down" pill is safer and more effective than one that is "dry swallowed."
From our sister publication, Diabetes Focus, Spring 2011