Glyset (miglitol): what it is and when to use it

Glyset is the brand name for miglitol, a pill used to help control blood sugar after meals in people with type 2 diabetes. It works in your gut to slow the breakdown of carbs, which smooths out blood sugar spikes after you eat. Doctors usually add it when diet, exercise, and one other diabetes drug don’t keep post-meal glucose in range.

How Glyset works and when it helps

Miglitol blocks enzymes called alpha-glucosidases in the small intestine. That means complex carbs reach the bloodstream more slowly, so your post-meal glucose rise is smaller. It’s meant for type 2 diabetes, not for type 1 or diabetic ketoacidosis. If your blood sugar problems are mainly after meals, Glyset can be a good fit.

Dosing, side effects and practical tips

Common tablet strengths are 25 mg, 50 mg and 100 mg. A typical start is 25 mg with the first bite of each main meal, three times a day. Your doctor may raise the dose to 50–100 mg TID depending on how you do and on your kidney function. Always take Glyset with food—the drug needs to be in the gut while you’re digesting carbs.

Expect GI side effects first: gas, bloating, and loose stools are the most common. These often ease after a few weeks as your gut adjusts. Less commonly, you might have abdominal pain. If these problems are severe or don’t improve, check with your prescriber.

Important safety note about low blood sugar: when Glyset is used with insulin or sulfonylureas, the risk of hypoglycemia rises. If you get low blood sugar while on Glyset, treat it with pure glucose (dextrose) — glucose tablets, gel, or juice. Table sugar (sucrose) and foods with sucrose won’t raise your blood sugar quickly because Glyset blocks the enzyme that breaks sucrose into glucose.

Don’t use Glyset if you have inflammatory bowel disease, colonic ulceration, intestinal obstruction, or certain malabsorption conditions. Also tell your doctor about kidney problems—dosing decisions rely on kidney function. Pregnant or breastfeeding? Talk to your clinician; options are usually chosen case-by-case.

Practical tips: stick to taking Glyset right at the start of each meal; skipping meals or taking the drug without food reduces its benefit. Keep a home glucose meter and log post-meal readings for a few weeks after starting or changing dose. That helps your provider see if Glyset is doing its job.

If you’re planning surgery, an endoscopy, or start a new medication, mention Glyset. Some procedures and drugs change how you eat or process carbs, and your care team may want to pause or adjust diabetes meds. Finally, report persistent stomach issues, frequent hypoglycemia, or any new symptoms to your healthcare provider promptly.