Thanks for writing to HCM I can understand your problem. The cause of the constipation may be due to( long standing) diabetes along with use of dicyclomine. It would have been of value if you had described if your IBS is type C, D or A. However Mebeverine might be an alternative choice. Since your are diabetic you must control your blood sugar level well within the target as high blood sugar over a long time will have Complications. Apart from sugar control get involved into mild to moderate intensity exercise as tolerated( if you are not having any heart problem & severe eye problem), drink plenty of water and keep hydrated and increase the fibre intake in your diet as well. Apart from this I just want to add something in general about Diabetes care: HbA1c undercontrol BP undercontrol, annual tests like Kidney Function Test(including micro albumin), Eye examination (retinal exam), Lipid Profile and ECG, if indicated, Dental examination. last by not the least a very good Foot Care is a must. Hope this helped. Do let us know.