Medically Reviewed By: Tom Iarocci, MD

If you’re a diabetic then you may already know how valuable it can be to measure your blood sugar levels at different points in any given day. The main goal of testing is to allow you to regulate your glucose levels and keep them as close to normal as practically possible. So, if your blood sugar is too high then you will adjust your diet accordingly. And if, for instance, you are on insulin and your blood sugar goes too low, you will also need to make adjustments.

Still, even among people who monitor their blood sugar levels regularly, there can be a lot of confusion about the sugar that you eat vs. the sugar that is in your blood, not to mention the effect of carbohydrates, fats, and proteins on your metabolism as someone living with diabetes.

Blood Sugar Versus Other Sugars:

Sugar is the term used to describe the sweet, simple carbohydrates that usually dissolve in water. There are different kinds of sugars in nature, including glucose, sucrose, lactose and fructose. If you think of your body as an engine that runs on certain types of fuel, when it comes to sugars your body’s fuel-of-choice is glucose, pure and simple. When people refer to blood sugar levels, they are referring to blood glucose levels.

In nature, glucose comes in many different packages, however—some of which are other simple carbohydrates and others are complex carbs or starches. For example, lactose is a simple carbohydrate, a sugar, made up of 1 molecule of glucose and 1 molecule of galactose. Common table sugar is sucrose, a simple sugar made up of 1 molecule of glucose and 1 molecule of fructose.

But glucose in nature also exists in chains, or starches. These starches are broken down during digestion to yield glucose, but this process is faster with some starches and slower with others, and the effects can be seen on blood sugar. For instance, if you eat processed carbs like white bread without fat or fiber in your meal, digestion is prompt, and this becomes glucose in your blood relatively quickly. In contrast, starches in beans and sweat potatoes tend to be digested more slowly, which may give you a more gradual, moderate rise in blood glucose.

What Is a Normal Blood Sugar Level?

The number of milligrams of glucose found in a deciliter of blood (mg/dl) measures your blood sugar level at any given time. What is considered normal in your case depends on whether you have diabetes, prediabetes, or are completely healthy. If you have a fasting blood sugar between 70 mg/dl and 100 mg/dl, this is considered normal, and is typical of non-diabetic people. Fasting levels are usually taken first thing in the morning, before eating or drinking anything. Fasting levels between 100 and 125 mg/dl are considered pre-diabetic, while levels 126 mg/dl or higher are indicative of diabetes. Another glucose level may be taken 2 hours after eating a meal, and this should be less than 140 mg/dl if you do not have diabetes. If you have diabetes, different goals after meals may apply to different people, but the American Diabetes Association suggests that less than 180 mg/dl may be an appropriate target for most nonpregnant adults with diabetes.

The A1C:

Unlike the home glucose checks, which might be compared to tests and quizzes in school, the A1C gives you a result that reflects all glucose exposures for a longer period of time—comparable to the grade for an entire semester of work. Your A1C number reflects the recent history of your blood sugar levels; it essentially averages out your glucose levels over a period of two to three months, and the result is given as a percentage.

A target A1C of 7% or below is a common goal of many people who have diabetes. Goal A1C ranges for different individuals, however, and your target may be higher or lower than 7% because of your specific characteristics as a person, a patient, and as someone living with diabetes.

Regular testing of your blood sugar level is relatively fast and easy. Blood glucose meters can take a single drop of blood and measure its sugar content in no time at all. The testing you do, together with adjustments you make at home, makes for better A1C results. Follow your doctor’s advice about the frequency and timing of your home glucose checks, as well as your goals.