Here is something I needed to research for a customer.
I am (time of writing) the marketing manager for a Spanish Coffee company. We produce sugar roasted coffee (torrefacto). If you like coffee and ever go to Spain, France, Portugal, Costa Rica or Argentina you should try Sugar Roasted coffee, it's pretty fantastic.
Sugar roasted coffee goes by the Spanish name "Torrefacto".
You can buy it as 100% sugar roasted coffee or blended with natural roasted coffee. A common blend for example would be 70% natural roasted coffee and 30% Sugar roasted coffee.
Basically the coffee is roasted in a roasting oven and late during the roasting process, sugar is added which caramelises to from a dark black glaze on the coffee.
What effects does it have:
1) Better flavour (subjective). The sugar roasting process reduces the acidity and help the natural coffee flavour to come through.
2) It increase the antioxidants in the coffee. Sugar Roasted coffee was found to have higher antioxidant properties than that of normal coffee.
3) Sugar roasted coffee darkens the coffee. Of course, the sugar goes dark so the coffee goes dark, this makes cappuccino and coffee with milk look beter.
Torrefacto and Diabetes:
The questions was raised. How does the sugar in sugar roasted coffee affect diabetics?
As far as I can tell diabetics don't need to change their habits when they drink Sugar roasted coffee. Sugar roasting creates a blackened glaze on the coffee which is produced by a process known as "Pyrolysis" and changes the chemical composition of sugar. This process breaks down sucrose into fructose and glucose. Fructose does not require insulin to metabolize and therefore can be enjoyed by people with insulin resistance problems (diabetics). Glucose on the other hand is something Diabetics need to know about. I'm sorry to say I don't know how much glucose would be in Torrecfacto coffee but from what I have read it is simply far less of a concern than the caffeine in coffee. Caffeine makes it harder for diabetics to control blood sugar levels, so if you are diabetic and want to drink coffee you should have already consulted a medical practitioner.
NOTE TO DIABETICS: I am NOT a doctor. I used wikipedia for my research and I also observed that no special notice is required to serve a customer sugar roasted coffee here in Spain (where I live). All I have used here is a bit of research and common sense, but I am not diabetic. If you are, at the end of the day you will know if the severity of your diabetes allows you to drink coffee and for sugar roasted you should simply be more carefull and consult a medical professional if you have any doubts.
PS. I would love some feedback from medical professionals and diabetics on this, please comment!