Normally when asked a question or required to write an article or dissertation on a subject, it's expected that the subject was part of the course.  That's not always the case - a few teachers see fit to take short-cuts and skip part of the instruction plan or text and the student doesn't take the initiative to study on his or her own.  Or perhaps you were out of class or not paying attention.

Diabetes, especially in a hospital setting, can be very touchy.  There are many levels and more than one type of diabetes.  Is the blood sugar under control?  Is the patient in for circulatory problems?  Is there a wound or surgical procedure involved (diabetics heal slowly unless their blood sugar is strictly in normal range).  Until you know a lot more about the patient's condition you cannot tell how much sugar they should eat, and that "sugar" even includes starches, fruits and even some veggies, etc. which the body can quickly convert to sugar.  The entire diet needs to be taken into consideration before desserts can be calculated individually for a diabetic patient.  In the USA this is usually done by a registered dietitian.

In any case, the best thing a diabetic can do is erase the word "dessert" from their vocabulary and mental library, and enjoy an abundance of green veggies, salads, beans and fish, and learn to use olive oil, ground flax seed and other Omega-3-rich food sources.  Desserts, by definition, are sweet.  If you remove the sugar, and usually the fruit and starch, too (depending on severity of disease and total meal plan) you probably have mostly non-nutritive material, real "junk food", something I'm entirely against!

Sugars include chemical compounds that end in "ose" (sucrose, fructose, maltose, lactose, etc.).  Sweeteners that do not raise blood sugar include aspartame, often marketed as Nutrasweet, saccharin and sucralose.  There is conflicting evidence about their toxicities and/or long term effects, with many scientists giving them the green light and others stern warnings.   Stevia, a plant extract, has been used in many countries for centuries for sweetening.  It does have a slight aftertaste, but no more so than aspartame or saccharin, just different.  It is not approved for sweetening in the USA although it is legal to buy it from "health food" stores or sites and utilize it for that purpose.  It would probably be inappropriate in a hospital setting. 

Looks to me like if they expect you to have to utilize this knowledge, you need to go back and hit the books!