digesting refined sugar and caffeine adversely affects blood sugar levels. when too much refined sugar is consumed the blood sugar level sky-rocker. But after an hour or so the blood-sugar level drops to a level far lower then before the sugar was eaten. this condition is caused by the over-secretion of insulin by the pancreas. caffeine
also can cause low blood sugar: thus anyone who just had a strong cup low blood sugar: thus anyone who just had a strong cup to coffee with heap tea-spoon of sugar in it for breakfast my feel hungry and fatigued an hour or two after he drink it.