1 OPINION. 2  The screening process for Syrian refugees is much more rigorous than for other visitors coming to the U.S. (AP Photo/Hassan Ammar)
About 250 milligrams of caffeine â or the equivalent of 2 to 2 1/2 cups (473 to 591 milliliters) of plain, brewed coffee â a day may cause this effect. If you have type 2 diabetes and you're struggling to control your blood sugar levels, limiting the amount of caffeine in your diet may provide a benefit.
However, consuming a large amount of caffeine daily or more than 250 mg of caffeine at a time can cause some unwanted effects. Too much caffeine can act to can speed up the heart rate, which can be dangerous for those with diabetes and heart problems. Those suffering from heart disease should limit their intake of caffeine to avoid experiencing any problems.