The way sugars in foods and drinks affect the amount of sugar in the blood is the glucose level. The Ideal range of blood sugar should be about 80 to 120. Blood sugar should be checked in the morning before eating anything. When too many carbohydrates are consumed an early morning fasting blood sugar test will show blood sugar levels above 120. This causes the blood to be thicker and harder for the heart to pump through the veins. Too much sugar in the blood will cause it to be thicker than normal. This is one reason untreated diabetes places one at increased risk for heart attack. The kidneys work to take the sugar out of the blood. High blood sugars can over time effect the kidneys. The kidneys play a role in blood pressure control. Increased blood sugars can raise blood pressure over time.
When there is too much sugar present in the blood it is called hyperglycemia or elevated blood sugar. The opposite situation where not enough carbs are consumed is called hypoglycemia or low blood sugar. Hypoglycemia can be a result of being more active than one normally would. This is why marathon runners will "carb up" before the marathon.
According to the American Diabetes Foundation the glycemic index or (GI) is a tool to help predict how much a certain food is going to affect the body's blood sugar levels. Foods are ranked on a scale of 1 to 100, with three basic divisions. 55 or less is low GI; some examples of these foods are oatmeal (rolled or steel cut), most fruits and non-starchy vegetables. 56 to 69 is medium GI, some foods in this category would be quick oats, whole wheat bread or rye bread. 70 or more is high GI, such as white bread or bagels, melons and pineapples. The scale is based on a comparison of pure glucose or white bread glycemic index as a reference.
Meats do not generally contain carbohydrates. This does not include processed meats like hot dogs and bologna which can have added carbohydrates. Fiber lowers the glycemic index in foods.
The glycemic index of a food is measured for a single serving. This means if the food is consumed in greater quantities it will have a greater impact on blood sugar levels. There is also a time factor at play when considering the impact on blood sugars. If lots of high glycemic index foods are consumed at one meal it will cause a greater rise in blood sugar levels. Mixing high glycemic index foods with low glycemic index foods can help lessen the effect. Spreading carbohydrate consumption out over all meals for the day helps lower the impact on blood sugars.
Part of the calculation of glycemic index of a food is how much fiber is in that food. 1 gram of fiber can subtract 1 gram of carbohydrates. This is part of the reason vegetables in general have a lower GI. Fiber does not increase the blood sugar level and aids in digestive tract health. It is thought that when high fiber foods such as vegetables are consumed in juice form this is even more beneficial to digestive health. Because there is less digestiving action required and therefore more benefits to be had. For example a stalk of celery has long fibrous cells which require a great deal of digestion to gain the available nutrition. If celery is juiced the fiber is still available but requires much less digestion to get the benefits of it.
The hypoglycemic index is only one tool available for understanding how food affects the body. Good health requires the use of many tools and good habits to maintain.