One of the definitions of “pre-diabetes” is a high rise in blood sugar after meals, and people with pre-diabetes are at significantly increased risk for suffering a heart attack or stroke (American College of Cardiology 70th Annual Scientific Session, May 16, 2021). Even if your fasting blood sugar is normal (below 100 mg/dL), you are at increased risk for a heart attack if you have a high rise in blood sugar after meals, because a high rise in blood sugar damages heart arteries (Diabetologia, 2021;64(2):275–287). Having a blood sugar level greater than 155 mg/dL one hour after eating:
• puts you at increased risk for forming plaques in your heart arteries (Atherosclerosis, Nov 2009;207(1):245-249)
• increases risk for arterial stiffness and high blood pressure (PLoS ONE, Sept 13, 2012)
• markedly increases risk for heart disease (Diabetes Metabolism, Feb 2019;35(2):e3096)

Diagnosing Type II Diabetes
Three tests are commonly used to diagnose Type II diabetes: fasting blood sugar, blood sugar level two hours after eating, and HbA1c, a measurement of how much sugar is attached to cells. The most dependable way to predict diabetes is to see how high blood sugar levels rise after meals. Many people have a fasting blood sugar level below 100 mg/dL, which is considered normal, so they are told by their doctors that they do not have diabetes and are never advised to change their unhealthful lifestyles. In one study, fasting blood sugar was normal in 21 percent of the people who had diabetes (European Heart Journal, Feb 13, 2015).

Forty percent of North Americans will become diabetic, and 65 percent of diabetics die of heart disease (N Engl J Med, Dec 22, 2005;353(25):2643-2653). Nearly 30 percent of people who have heart problems have Type II diabetes and many do not know it. High rises in blood sugar cause cell damage and your blood sugar levels rise highest after you eat. A fasting blood sugar level test will not pick up those who have a high rise in blood sugar only after meals. If your blood sugar is over 145 mg/dL two hours after a meal, you are at double the risk for a heart attack (Diabetes Care, October 2011;34(10):2237-2243).

My Recommendations
People who have fasting blood sugar levels between 100 and 125 mg/dL are often told that they have “pre-diabetes,” when they are already at very high risk for heart attacks (BMJ, 2016;355:i5953). In my opinion, using the term “pre-diabetes” will kill a lot of people because extensive damage is done to cells throughout your body when your blood sugar rises too high after meals, even if your fasting blood sugar level is normal. I believe that you should be told that you are already diabetic if your blood sugar rises above 155 mg/dL one hour after you eat a meal. Most cases of type II diabetes are caused by inability to respond adequately to insulin, which can be cured with lifestyle changes but not with drugs.

More than seventy percent of people with pre-diabetes eventually develop Type II diabetes (Diabetes Care, 2020;43 (Suppl 1):S32-6), so I think that everyone should get a test for blood sugar one hour after eating. If it is greater than 145 mg/dL, you may not need drugs, but you should make major lifestyle changes: avoid sugar-added foods, all drinks with sugar in them including fruit juices, and other refined carbohydrates (foods made from flour). You may also need to lose weight and start an exercise program. See Prevent Diabetes with Exercise and a Plant-Based Diet
High Blood Sugar After Meals Predicts Heart Attacks