By Dr. Harry G. Preuss MD,

Much of my recent research deals with the proposition that the common measurement of fasting blood glucose (FBG) levels, a routine procedure in most doctors’ offices, is a convenient and useful surrogate (representative marker) for insulin resistance (IR)(1).  IR occurs when there is some impediment to the action of insulin in peripheral tissues like muscle and liver. To compensate, the pancreas makes and releases more insulin into the blood stream to counteract gradually rising concentrations of glucose. The compensation is usually not complete and leads in time to elevated circulating levels of both glucose and insulin.  

Being a surrogate for IR is extremely important.  Not only can noteworthy IR , left unchecked, eventually bring about diabetes and is markedly involved in the “epidemic” of this unfortunate entity; but perhaps even more important, the strength of IR estimated by the measure of FBG short of a diagnosis of diabetes is being associated with many common, chronic disabling medical maladies – many mentioned below [1,2].

To be more precise, even though doctors are primarily concerned with diagnosing diabetes when the FBG reading consistently exceeds 125 mg/dl, a meaningful alarm is set off in the more astute physicians if the reading exceeds 100 mg/dl.  The latter implies that a pre diabetic stage with increasing IR has been reached leading a few practitioners to believe that preventive measures should be implemented ASAP – usually through modifications in diet and exercise. I have reason to accept as true that the use of FBG as a surrogate, even in the non diabetic range but at the high end of normal, would allow an even earlier warning for initiating a preventive program. Suffice it to say, IR is receiving mounting attention because of it close association with many chronic, severe age-related health maladies — particularly cardiovascular ones (2). 

An earlier start of meaningful measures would obviously lead to more definitive success in deterrence. To add another important point, diabetes is also recognized widely to be a form of premature aging and severe IR is an important part of this pathology.  Accordingly, early protective measures might also show the way to a longer, healthier lifespan. This led me many years ago to propose that even mild forms of IR that are routinely ignored could hasten the aging process over time [3,4]. That is why recognition of FBG as a potential surrogate to measure early, milder IR is so important.

Over the last couple of years, I have been amazed at how closely the circulating concentration of FBG in normal non-diabetic individuals has with early stages of a multitude of chronic maladies including obesity, high blood pressure, abnormal levels of blood lipids like triglycerides and HDL-cholesterol – the good and bad lipids.  Most interesting is what happens to these correlations with aging. When examining subjects over a wide age span (21 – 84 years), a revealing aging paradox was found to occur somewhere in the 60-70 year age range (See figure below).

Fig. 1.  Average yearly FBG at various ages.

In Fig. 1, a cross section of over 10,000 females (77%) and males (23%) of differing ages were followed from youth to older age, i.e., 21 to 84 years (1).  As a first approximation, singling out those between ages 21-64 years, the FBG rose steadily in a significant manner along with various risk factors for the chronic health disorders, particularly cardiovascular.  Although many measurements still remained in a range most laboratories and the reading physicians would accept as normal, still, does it represent a healthful state to see routine, gradual enhancement of FBG during the early lifespan?  Worth repeating, along with IR increasing, obesity, higher BP, and elevation of bad lipids follow suit. I’ll get to this point in future communications, but what I wish to emphasize now is that somewhere around age 65 years in “normal, relatively healthy” individuals, the FBG (my surrogate for IR) begins to decrease steadily and significantly, i.e., to indicate recovery in IR.  Along with this fall off, improvements occurred not only in the diabetic measurement, but also in body composition, in blood pressure, and in circulating triglycerides and HDL-cholesterol.  

Trust me, the immediate, above-mentioned findings could be very important for your overall health and desire to have a long, healthy lifespan.  I will pick up on this matter in my next report, but just as a teaser, remember the term, “survivor bias.”

References

  1. Preuss HG, Mrvichin N, Bagchi D, Preuss J, Perricone N, Kaats GR: Fasting circulating glucose levels in the non-diabetic range correlate appropriately with many components of the metabolic syndrome. The Original Internist 23:78-89, 2016.
  2. DeFronzo RA, Ferinimmi E: Insulin resistance: a multifaceted syndrome responsible for NIDDM, obesity, hypertension, dyslipidemia, and atherosclerotic cardiovascular disease. Diabetes Care 14:173-194, 1991.
  3. Preuss HG: The insulin system in health and disease (Editorial). J Am Coll Nutr 16:393-394, 1997.
  4. Preuss HG: Effects of glucose/insulin perturbations on aging and chronic disorders of aging: the evidence. J Am Coll Nutr 16:397-403, 1997.

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