A sudden tripling of blood sugar while on a maximum dose of Diamicron (Gliclazide) is a serious concern requiring urgent medical evaluation. This spike could be triggered by an infection, physical stress, or a decline in her pancreas's ability to produce insulin. Do not change her medication dose yourself. Please contact her doctor or visit an emergency room immediately to prevent dangerous complications like diabetic ketoacidosis. Her physician will likely need to adjust her treatment plan, which may involve adding other oral medications or starting insulin therapy to safely stabilize her blood sugar.