glycated hemoglobin is usually 4–6% by the most common methods (normal ranges may vary by method). "Perfect glycemic control" would mean that glucose levels were always normal (70–130 mg/dL, or 3.9–7.2 mmol/L) and indistinguishable from a person without diabetes. In reality, because of the imperfections of treatment measures, even "good glycemic control" describes blood glucose levels that average somewhat higher than normal much of the time. In addition, one survey of type 2 diabetics found that they rated the harm to their quality of life from intensive interventions to control their blood sugar to be just as severe as the harm resulting from intermediate levels of diabetic complications. In the 1990s the American Diabetes Association conducted a publicity campaign to persuade patients and physicians to strive for average glucose and hemoglobin A1c values below 200 mg/dL (11 mmol/L) and 8%. Currently, many patients and physicians attempt to do better than that. As of 2015 the guidelines called for an HbA1c of around 7% or a fasting glucose of less than 7.2 mmol/L (130 mg/dL); however these goals may be changed after professional clinical consultation, taking into account particular risks of hypoglycemia and life expectancy. Despite guidelines recommending that intensive blood sugar control be based on balancing immediate harms and long-term benefits, many people – for example people with a life expectancy of less than nine years – who will not benefit are over-treated and do not experience clinically meaningful benefits. Poor glycemic control refers to persistently elevated blood glucose and glycated hemoglobin levels, which may range from 200 to 500 mg/dL (11–28 mmol/L) and 9–15% or higher over months and years before severe complications occur. Meta-analysis of large studies done on the effects of tight vs. conventional, or more relaxed, glycemic control in type 2 diabetics have failed to demonstrate a difference in all-cause cardiovascular death, non-fatal stroke, or limb amputation, but decreased the risk of nonfatal heart attack by 15%. Additionally, tight glucose control decreased the risk of progression of retinopathy and nephropathy, and decreased the incidence peripheral neuropathy, but increased the risk of hypoglycemia 2.4 times. Monitoring Relying on their own perceptions of symptoms of hyperglycemia or hypoglycemia is usually unsatisfactory as mild to moderate hyperglycemia causes no obvious symptoms in nearly all patients. Other considerations include the fact that, while food takes several hours to be digested and absorbed, insulin administration can have glucose lowering effects for