The bad choices to add to coffee are sugar, artificial sweetener, non-dairy creamers, artificial flavor shots, and skim milk. Considering the variety of reasons of its ill-effects, a lot of which is that it has a lot of man-made ingredients. Where as a few drops of cinnamon, peppermint, or vanilla for a natural, sugar free shot of flavor are better choices to add up to your coffee. Also milk is the right option as it actually reduces the risk of diabetes.
The worst of the worst that might be added to coffee are the Nondairy Creamers (Coffee Mate), the creamer often has an ingredient with corn syrup and partially hydrogenated vegetable oils. Corn syrup is similar to sugar and empty calories, and the partially hydrogenated oils are trans fats that are man made and bad for the health.
Coffee mixed up with squirts of vanilla, hazelnut, caramel, or pumpkin spice is like having pure cane sugar and artificial colors. Better to add up a few drops of vanilla, peppermint, or various nut extracts to your coffee and all are naturally sugar free.
Studies prove that the zero-calorie sweeteners are substitutes to things like impaired glucose metabolism, which may give a person food craving and boost the risk of diabetes. It can also give disorder in a person's gut bacteria. Experts suggest stevia leaf extract is likely a better alternative.
Moderate sugar intake won't hurt a person, but if a person drinks several coffees per day, the calories will pile up fast. For just 2 tsp of sugar added to a person's daily three cups of coffee has a running total of 48 g of sugar, that's more than a can of Coke intake. The clean alternative is just to add a few dash of cinnamon, where cinnamon has a natural sweetness despite being sugar free. Studies show cinnamon can actually prevent spikes in blood sugar.
A lot of research suggests that the full-fat 'Skim milk' might be better, and the study shows that people who regularly consume whole-fat dairy ate fewer carbs while people who consume low and nonfat dairy ate significantly more carbs.