You have a job that requires concentration. The caffeine and sugar in the soda provide quick concentrated "brain food". I am not passing judgement on sugar and caffeine. I eat both of these things myself, but in moderation. So you are asking for alternatives.
Why don't you schedule an appointment with your doctor? Discuss your situation and family history with your doctor. Also ask the doctor about some longer lasting food/beverage alternatives. The doctor may refer you to a registered dietician for a consultation.
You may have to move away from "tasty", because I doubt you are really seeking good taste (super-concentrated taste) in the beverage; what you are probably really seeking is the quick concentration and energy that sugar-caffeine provide. I have mentioned green tea sweetened with stevia. You might also discuss with the doctor the bottled water "Gerolsteiner". Yes, a form of bottled water! Remember water? No, it will not taste as good as soda. :)
I don't know if what I have said constitutes medical advice or not according to the rules of this site. I am sure the mods will alert or remove if my answer crosses the line. I want to follow the rules here, so if the mods feel that this answer should be removed, then they should feel free to remove it. What you are ideally seeking is hydration and slower burning, but substantial, foods overall.
P.S. Regarding other preventive measures, see: "Our recent human studies indicate that consuming roughly one half of a teaspoon of cinnamon per day or less leads to dramatic improvements in blood sugar, cholesterol, LDL-cholesterol and triglycerides." https://www.ars.usda.gov/northeast-area/docs/cinnamon-health-benefits/research/
"However, not all studies have shown positive effects of cinnamon, and type and amount of cinnamon, as well as the type of subjects and drugs subjects are taking, are likely to affect the response to cinnamon. In summary, components of cinnamon may be important in the alleviation and prevention of the signs and symptoms of metabolic syndrome, type 2 diabetes, and cardiovascular and related diseases."
Note: cinnamon, not cinnamon-sugar!
Type of cinnamon: https://www.google.com/amp/s/amp.peoplespharmacy.com/posts/which-cinnamon-is-better-for-blood-sugar
So getting some cinnamon in the diet could also be something to discuss with your doctor.