If you have diabetes, how tightly should you control your blood sugar levels? "Tight control," keeping your blood sugar levels as close to normal as possible, has been a bedrock principle in managing diabetes, as long as you avoid dangerously low blood sugar (hypoglycemia).

Long-term glucose control is measured with a glycohemoglobin A1C blood test. Many doctors recommend a maximum result of 7 percent (which translates to a glucose level averaging 135 mg/dL overall for the previous three months) or even 6.5 percent (average glucose of 120 mg/dL for the prior three months).

Earlier this year, however, a study from the ACCORD project (Action to Control Cardiovascular Risk in Diabetes) found that tight control of glucose (glycohemoglobin A1C averaging 6.4 percent vs. 7.5 percent in the standard treatment group) actually increased patients' risk of death by 22 percent. Although the results sound alarming, experts said they probably didn't apply to the general diabetes community because many of the subjects were high-risk, which can make hypoglycemia more dangerous.

Other recent studies back up the benefits of tight blood-sugar control:

• In a follow-up to the landmark United Kingdom Prospective Diabetes Study, patients with type 2 diabetes who tightly controlled their glucose in the first decade after diagnosis (glycohemoglobin A1C averaging 7 percent vs. 7.9 percent in the standard group) had a reduced risk of heart attack and death years later. Doctors called this long-term benefit a "legacy effect" of early tight control of glucose. "Now, I can go back to my clinic and tell my patients that even though they are not perfect, the good control they have achieved will have long-lasting effect," said researcher Ping H. Wang, M.D.
  
  
• Intensive glucose control (glycohemoglobin A1C averaging 6.5 percent vs. 7.3 percent in the standard group) decreased patients' risk of developing kidney disease by 21 percent, according to an international project called ADVANCE (Action in Diabetes and Vascular Disease).

Diabetes specialists, including those involved in the ACCORD study, continue to emphasize good control of glucose because hyperglycemia can devastate the heart, nerves, eyes and other organs. Exercise, diet, pills and insulin, as prescribed by a doctor, are all ways to control glucose.

"For now, any strategy that lowers glucose and is associated with a low risk of hypoglycemia and does not cause excessive weight gain should be considered appropriate," ACCORD researcher Byron J. Hoogwerf, M.D., wrote in the October 2008 issue of the Cleveland Clinic Journal of Medicine.

So what should your target glucose range be? Your doctor will set a goal based on many factors. For example, patients who are at increased risk for hypoglycemia or have hypoglycemia unawareness (difficulty sensing low blood sugar) may have a higher range than most. Others, such as women planning for pregnancy, may be advised to have especially strict control of their glucose.

Keeping that in mind, here are general ranges for diabetic glucose monitoring:

• Before meals: 90 to 130 mg/dL (plasma)
  
• One to two hours after the start of a meal: 180 mg/dL and lower (plasma)
  
• Bedtime: 110 to 150 mg/dL

Ask your doctor what your glucose and glycohemoglobin A1C targets are, how often you should check your levels and how you can best achieve your goals.

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