Employee & Community Health

Managing blood glucose: Finding the right balance

1/11/2018 by Dr. Rozalina McCoy

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Treating diabetes requires balance — balancing the disease and other health problems, balancing mental and physical health, and balancing medical and other life demands. It also requires a balance between the likely benefits and potential harms of treatment and lowering blood glucose (blood sugar). 

Diabetes is recognized by elevated blood glucose levels caused either by your body's lack of insulin production (type 1) or it's progressive resistance to insulin (type 2). Uncontrolled diabetes and high blood glucose levels affect almost every part of your body. Diabetes: 

  • Is the most common cause of blindness, kidney failure and amputations
  • Significantly increases the risk of heart disease and strokes
  • Is the seventh leading cause of death in the U.S.
  • Affects the nerves causing symptoms such as painful neuropathy, unstable blood pressure and pulse, gastroparesis, diarrhea and constipation
  • Affects your teeth and gums, mood and immune system

Testing for blood sugar levels

Controlling blood sugar levels is key to reducing the risk of these complications. There are two ways to measure for diabetes control: 

  • Fasting blood glucose levels, measured either using a finger stick and glucose monitor or a laboratory blood test. Both tests tell us the current blood sugar level. 
    • Normal, 100 mg/dL or lower
    • Prediabetes, 101-125 mg/dL
    • Diabetes, 126 mg/dL and above
  • Hemoglobin A1c (HbA1c) measures the percentage of hemoglobin (red blood cells) with glucose attached to them. Because these levels have a lifespan of about 120 days, HbA1c reflects the average glucose level during the past 120 days. Normal HbA1c levels may vary for different ethnic populations, children and people with certain health conditions, but general results are: 
    • No pre-diabetes or diabetes, less than 5.7%
    • Pre-diabetes, 5.7-6.5%
    • Diabetes, above 6.5%

Very high blood sugar levels — above 180 mg/dL — can cause immediate symptoms such as confusion, frequent urination and thirst, blurry vision and weakness. HbA1c of 8% corresponds approximately to a fasting blood sugar of 183 mg/dL. 

Lowering HbA1c

Multiple studies have looked at the link between lowering HbA1c and reducing risk of microvascular (eye, kidney and nerve) and cardiovascular (heart disease and stroke) complications. Lowering HbA1c has the greatest effect on microvascular complications and plays a bigger role in type 1 than type 2 diabetes. This is likely because people with type 2 often have other chronic diseases with overlapping health complications, including high blood pressure, high cholesterol and excess weight. 

HbA1c doesn't need to be reduced all the way down to normal. The most benefit comes from lowering HbA1c to less than 8%, with very little added benefit from decreasing HbA1c to 7% or lower. Also, it takes a long time to see the benefits of lower HbA1c. Most studies required at least 10 years to see any benefit for microvascular complications and even longer for reducing cardiovascular problems. 

Lower blood sugar

Trying to lower blood sugar too much, particularly when using several medications or medications such as insulin or sulfonylureas (chlorpropamide, glipizide, glyburide, glimepiride), can lead to levels that are too low. 

This condition is called hypoglycemia, which can cause confusion, irritability, shakiness and heart rhythm problems. If not recognized and treated, it can progress to loss of consciousness, seizure, coma or even death. Long term, it increases the risk of heart disease, dementia and death. 

Blood sugar levels under 70 mg/dL can be harmful and should be treated promptly, including assessing why it happened and identifying steps to prevent it from happening again. 

People at risk for hypoglycemia should be cautious and strive for slightly higher blood glucose and HbA1c targets. This includes those who have a history of hypoglycemia, hypoglycemia unawareness (few or no symptoms until it is severe) or multiple chronic conditions, kidney or heart disease, dementia or cognitive impairment. 

Because it takes many years to see the benefits of lower HbA1c, people with limited life expectancy (less than five to 10 years) don't need to lower their blood glucose to very low levels. 

For most people with diabetes, an HbA1c less than 7% is preferred, but only if this can be achieved safely, without significant hypoglycemia, medication side effects or making treatment too difficult for patients. 

  • Those who are young, healthy and have no major health concerns may consider a target of less than 6.5% for HbA1c. 
  • Those who are at risk for hypoglycemia, have limited life expectancy or can't tolerate intensive treatment, may benefit from higher targets, such as 8%-9%. 

Finding the right balance

Balance changes over time, so something that was right for you before may not be right for you now. That's why it's very important to talk with your health care team about your goals, preferences and concerns, and work together to identify the diabetes treatment plan and regimen that are right for you. 

Dr. Rozalina McCoy is an endocrinologist and primary care physician in Employee and Community Health's (ECH) Division of Primary Care Internal Medicine (PCIM) in Rochester. She specializes in the management of type 1 and type 2 diabetes, osteoporosis and thyroid disorders. Dr. McCoy also is a health services researcher who is passionate about improving the care of patients with diabetes, reducing their burden of treatment and hypoglycemia, and working with community-based organizations to help everyone access evidence-based health-promotion programs.