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.
In the presence of caffeine, adenosine can't find to its receptors, so your brain becomes more active. It sends stimulating signals to your body -- including your cardiovascular system -- and these signals trigger an increase in heart rate and blood pressure.owever, 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.