What You Don’t Know About Blood Sugar

William Faloon

The most cherished benefit of Foundation membership is discovering something new in every Life Extension publication. Unlike typical health journals, we inform members about what they don’t know concerning medical findings that are overlooked by conventional and alternative doctors.

In our relentless review of the scientific literature, we have uncovered data that calls into question what the safe range of blood sugar really is. Current guidelines state that a person is diabetic if fasting blood glucose levels exceed 126 mg/dL on two consecutive occasions. Fasting glucose levels over 109 are flagged as potential prediabetic (glucose intolerant) states. Life Extension has long argued that optimal glucose ranges are less than 100.

In a new hypothesis that shakes the pillars of conventional wisdom, it now appears that optimal fasting blood glucose levels should probably be under 86 mg/dL. This means that those with high “normal” glucose (86-109) are at an increased risk of premature death. While the medical establishment clearly understands the lethal dangers of hyperglycemia (blood sugar over 126), they have yet to recognize that even high normal glucose levels pose a serious threat to one’s health.

Why “Normal” Glucose Levels Are Dangerous

To support our hypothesis that higher“normal” ranges of blood glucose represent a health risk, we first investigated the multifaceted toxic effects that sugar inflicts throughout the body. We found many studies showing that sugar damages cells via multiple mechanisms and is a causative factor in common diseases of aging.1-37 It thus appears desirable to maintain the lowest level of blood glucose needed to sustain healthy metabolic function.

We then looked at the effects of caloric restriction, and noted one study in which fasting glucose declined from an average of 92 to 74 mg/dL in a group of adults who reduced their food intake.38 This corresponded to animal studies in which caloric restriction induced significant reductions in blood glucose levels.39-41 It is well established that cutting calorie intake reduces one’s risk of age-related diseases and probably slows aging itself.42-50 One reason for this may be the reduction in blood glucose levels that occurs in response to ingesting fewer calories.

As people age, their fasting glucose levels normally increase as their health declines. Standard laboratory reference ranges show an aging person having a “normal” fasting glucose level of up to 109 mg/dL. Yet the most effective anti-aging therapy—caloric restriction—lowers glucose levels to the low 70s (mg/dL).

Many theories of aging focus on the deleterious effects of glucose itself. Only a few studies have evaluated disease risk in people whose fasting blood glucose levels are in normal ranges. One study of nearly 2,000 men looked at fasting blood glucose levels over a 22-year period. Its startling results showed that men with fasting glucose levels over 85 mg/dL had a 40% increased risk of death from cardiovascular disease. The researchers concluded, “fasting blood glucose values in the upper normal range (appear) to be an important independent predictor of cardiovascular death in nondiabetic apparently healthy middle-aged men.”51

A light micrograph of a human pancreas. The pancreas is a digestive gland, but also controls blood sugar levels by secreting insulin.

Foundation members often have their blood tested through our discounted mail-order blood-testing service. In addition to using the results of these blood tests to improve members’ health, Life Extension is able to use this information to evaluate trends that can lead to better recommendations for extending longevity. We compiled data from all fasting glucose tests conducted over the past 12 months. The average reading was 94 mg/dL. While physicians would consider this “normal” result to be excellent, our new hypothesis indicates that optimal glucose levels should be below 86 mg/dL (and ideally as low as 74 mg/dL).

Where Your Pancreas Thinks Glucose Levels Should Be

The pancreas plays a major role in regulating blood glucose levels by secreting insulin to transport sugar out of the blood and into cells for energy production or storage.

Insulin also drives fat into cells, prevents fat from being released from cells, and makes people hungry. High insulin levels contribute to obesity and the disease states associated with being overweight, such as type II diabetes, cardiovascular disease, kidney failure, and certain types of cancers.

In normal health, the pancreas stops secreting insulin when glucose levels drop below 83 mg/dL.52-54 As I noted earlier, healthy aging people typically have fasting glucose levels over 90 mg/dL, and even competent doctors wait until fasting glucose is over 109 before suspecting a pre-diabetic (glucose-intolerant) condition.

But insulin continues to be secreted when blood glucose levels are over 83 mg/dL, which indicates that the pancreas is striving to drive glucose levels down to a range safer than what aging people typically are able to achieve.

An in-depth discussion about the lethal dangers of excess insulin can be found in the chapter on obesity in our Disease Prevention and Treatment reference book (4th edition). In the obesity protocol, we present evidence that excess insulin is a causative factor for body fat accumulation.