When I checked on the safety of a type 2 diabetic taking Mucinex DM I was told it is safe. The active ingredients are Guaifenesin an expectorant and Dextromethorphan a cough suppressant should not change blood sugar levels. The inactive ingredients consist of carbomer 934P, NF; D&C yellow #10 aluminum lake; hypromellose, magnesium stearate, microcrystalline cellulose, sodium starch glycolate. None of them should effect either. To be sure you may want to monitor your levels closer while using this or any medication. Always check with your physician before taking any medication. You can also talk to a pharmacist about any concerns you have, or possible side effects.