If you want to reduce your A1c levels, you should manage what you eat and pay particular attention to sugar intake and carbs. Healthy food choices and meal timing, in combination with exercise will help your body do its best to control your blood sugar levels.
Here are some resources about eating healthy meals and nutrition for people with diabetes.
Some studies have shown that drinking coffee or tea is associated with decreased incidence of diabetes. The Leibniz Center for Diabetes Research reported that drinking four cups of tea a day has a 20% lower risk of developing diabetes - this conclusion drawn from studying 12,000 Type 2 diabetes patients throughout Europe. For a pre-diabetic individual, drinking coffee or tea every day may be beneficial in the long term.
As a powerful stimulant, caffeine increases heart rate. Be careful on hot sunny days and avoid excessive caffeine. When you are active in the heat, caffeine can increase your blood glucose levels dramatically.