Fasting Blood Sugar Can Be Too Low


A low fasting blood sugar or an abnormally low HbA1C (a test of the amount of sugar stuck on cells) may increase risk for heart attacks. Researchers followed almost 5000 people for 13 years and found that having a very low fasting blood sugar (<80 mg/dL) and very low HbA1c (<5.0 percent) is strongly associated with increased risk for heart attacks and premature death (J Endo Soc, 2019;3(5):892-901).

Low blood sugar is often caused by high levels of insulin which increase risk for heart attacks by:
• causing salt retention to raise blood pressure
• blocking nitric oxide to constrict arteries leading to the heart
• raising triglycerides
• raising small dense LDL cholesterol that can form plaques in arteries
• increasing clotting that is the eventual cause of a heart attack
High insulin levels also increase cancer risk by stimulating excess cell growth and insulin-like growth factor.

Many previous studies have established that having high fasting blood sugar (>100 mg/dL) and/or high HbA1C (>5.7) are signs of diabetes and increased risk for heart attacks and premature death. At the present time, doctors define diabetes as having a fasting blood sugar >125, but that misses more than 30 percent of diabetics who are at high risk for heart attacks because of their high blood sugar levels that show up only after they eat. You are diabetic if your blood sugar rises over 145 mg/dL one hour after you eat, even if your fasting blood sugar is normal (Diabetes Care, 2001;24(8):1448-1453).

My Recommendations
If you have a fasting blood sugar level below 80 mg/dL or HBA1C below 5, you may have low blood sugar levels caused by high insulin levels that increase risk for heart attacks, certain cancers and premature death. Your doctor should order tests for:
• blood sugar level one hour after a full meal
• blood insulin level

If your blood sugar one hour after a meal is greater than 145 or you have high insulin levels, you may not need drugs, but you need to make the same serious changes in lifestyle as a diabetic:
• Eat vegetables, nuts and other unprocessed plant foods that are full of fiber that helps to prevent diabetes
• Limit or avoid processed foods, particularly foods and drinks with added sugars and foods made from flour (bread, pasta, many dry breakfast cereals, pretzels, bagels and so forth)
• Avoid being overweight, particularly if you store excess fat in your belly
• Try to exercise for at least 30 minutes every day

Checked 6/8/23