When you were diagnosed with diabetes, your doctor probably told you that your blood glucose levels were too high. Indeed, high blood glucose, or hyperglycemia, is the hallmark of diabetes. Regardless of your knowledge of diabetes at that time, you may have wondered what the significance of high blood glucose levels was for you. The answer is that hyperglycemia is linked to the development of long-term diabetes complications, which include nephropathy (kidney disease), retinopathy (eye disease), neuropathy (nerve damage), foot and skin problems, heart and blood vessel disease, and tooth and gum disease. That’s why individual treatment plans for people with diabetes focus on preventing hyperglycemia and keeping blood glucose levels as close to the normal range as possible. Keeping blood glucose levels close to normal requires learning how to balance food intake, physical activity, and the effects of any diabetes medicines your doctor may prescribe to lower your blood glucose level. For some people, the balancing act also involves learning to avoid hypoglycemia, or low blood glucose.
Blood glucose goals
In healthy people who don’t have diabetes, blood glucose levels typically run in the range of 65–110 mg/dl and may rise to 120–140 mg/dl one to two hours after eating. A diagnosis of diabetes is made when a person’s fasting blood glucose level is above 126 mg/dl on two separate occasions or when a person has symptoms of diabetes (such as excessive thirst and urination) and his nonfasting blood glucose level is greater than 200 mg/dl on two separate occasions.
Until recently, a diagnosis of prediabetes, a condition in which blood glucose levels are high but not high enough for a diagnosis of diabetes, was made when a person’s fasting blood glucose level was between 110 mg/dl and 126 mg/dl. More recently, an international expert committee on diabetes recommended diagnosing prediabetes when a person’s fasting blood glucose level is 100 mg/dl, and the American Diabetes Association (ADA) has adopted this recommendation.
On the basis of research showing that maintaining near-normal blood glucose levels significantly reduces the risk of diabetes-related complications, both the ADA and the American College of Endocrinology (ACE) have established recommended goals for blood glucose control for most adults with diabetes (see “Blood Glucose Targets”). These goals may be modified for certain populations. For example, the goals for blood glucose control are typically lower for women with diabetes who are pregnant. For children and the elderly, particularly those who take insulin as part of their treatment plan, the goals may be higher for safety reasons. Because each person’s situation is different, it is important to work with your diabetes care team to set individualized blood glucose goals that are right for you.
Two significant studies that paved the way toward today’s blood glucose goals are the Diabetes Control and Complications Trial (DCCT) and the United Kingdom Prospective Diabetes Study (UKPDS). Both demonstrated that the closer blood glucose levels are kept to normal, the less likely a person with diabetes is to develop complications.