Knowing All About Sugar Essential for Life but Potentially Unhealthy Part 1 of the Diabetic Story

Sugar is the familiar and common name for sucrose, a naturally occurring substance in nature that is formed in plants from the combination of water absorbed from soil and carbon dioxide absorbed from air. Yes, sugar is composed simply of water and carbon dioxide. 

Sucrose is a complex sugar composed by the union of two smaller, simpler sugar molecules: glucose and fructose.  Glucose and fructose and sucrose are each composed in nature as unique and independent compounds of carbon dioxide and water, and each exists as essential energy supplier compounds when ingested by animals of all kinds.  

Focusing on us humans, the compound “sucrose” is not absorbable as the double sugar. It must be cleaved into its two component parts: fructose and glucose.  These are then separately absorbable by our intestinal tissues. The breakdown of sucrose into its components of fructose and glucose occurs within our digestive tracts as ingested carbohydrate foods move from our mouth through our stomach and small intestine. Enzymes secreted by our salivary glands and pancreas split sucrose into its two components, and then glucose is easily absorbed across the intestinal wall into our bloodstream.  

Once absorbed, glucose serves as our basic and essential energy molecule for each tissue cell - of all types and ages in our body. The journey of glucose is to travel in our bloodstream which bathes all of our tissues until each glucose molecule is transported into our numerous specific tissue cells where glucose serves as our primary tissue energy supplier. And, most important at this juncture is that insulin is a required facilitator for the transport of glucose from our bloodstream into our cells. 

Within our numerous tissue cells, it is most amazing that the glucose molecule becomes split into water and carbon dioxide, just as it commenced its existence in plant leaves. Thus, from carbon dioxide and water in plant leaves, the glucose molecule is formed, eventually eaten, enters the human body, travels throughout our blood stream, is transported into numerous varying widely differentiated tissue cells, and then is changed back into carbon dioxide and water, while energy molecules (such as ATP) are generated for the essential support of the tissue cell life.  

The other component of sucrose is “fructose.”  Fructose is split from sucrose just like glucose. The journey of fructose, however, differs from the journey of glucose.  Fructose is absorbable across our intestinal lining similar to glucose, and fructose does enter and circulate within our bloodstream. However, fructose does not have entry into other tissue cells (with one exception, the sperm cell).  Thus, fructose cannot supply immediate energy for all other tissue cells.  Rather, the fructose molecules rather quickly enter our liver cells where they are joined into chains and stored there as “starch” and “fat”, existing in those forms as “energy reserves” that may be released over several hours back into our bloodstream as needed and when needed after ingested circulating glucose molecules are “used up.” 

Once again, this is an amazing energy economy from consumed plant foods: immediate energy (from glucose) plus stored energy reserves (starch, glycogen, fat from fructose).

As briefly mentioned, the hormone insulin is an essential glucose-transport regulator. Insulin exists to “drive” glucose into our vital organ cells. Our pancreas “detects” glucose molecules directly after absorption from the intestine and then secretes insulin, which travels in the bloodstream to direct the uptake of glucose into our vital organ cells. Insulin is essential. Glucose uptake into our critical tissues will not occur without insulin. This insulin response is sensitive, predictable, and highly regulated and governed, such that just enough insulin is produced and secreted to match the glucose surge from eaten foods. Thus, any large surge of glucose from plant food ingestion is minimized because the newly-absorbed and now circulating glucose is rapidly transported into tissues by the action of insulin on tissue cell membranes to relocate glucose from blood into the interior of tissue cells.

Essential life facts: 

• Glucose is our chief energy supplier; 
• Glucose cannot gain entry into our tissues without insulin; (one exception is our red blood cells which carry hemoglobin and oxygen; glucose enters our red blood cells without the transport-aid of insulin); 
• Insulin secretion is stimulated by any glucose surge into our blood;
• Insulin secretion matches glucose concentrations in our blood;
• Glucose is always available in our bloodstream because when the eaten glucose surge exits our bloodstream, our stored-in-tissue starch will slowly and steadily release ‘new glucose’ molecules that circulate and are used for essential life functions. 
• Remember that starch formation is one fate of ingested fructose as well as ingested glucose, and these storage deposits in our liver exist just for the purpose of slow release of fresh glucose when we are not eating.  
• In this way, glucose in our bloodstream is maintained at life-sustaining concentrations, always available for entry into vital organ cells for energy generation within the cells.
• While fasting, our plasma glucose concentration will reside between 70 mg/dL and 99 mg/dL. With a snack or meal, our glucose surge should not rise above 125 mg/dL, no matter how much sucrose or simple glucose  or other complex sugars we have eaten. Our pancreas' response with insulin output is set to match the glucose entry. 
• AND, very importantly, the entering glucose into our bloodstream will NOT circulate in the bloodstream for more than 90 minutes. The ingested ‘new’ glucose will be transported into tissues rapidly. 
• Insulin secretion thus declines as glucose concentrations decline to levels below 100 mg/dL, and this response allows glucose concentrations to settle in the range of 70­ to 99 mg/dL. 
• AND, glucose molecules liberated from stored starch deposits will circulate only about 90 minutes as well, as each ‘newly released’ glucose molecule is also transported quickly into tissue cells by the ever-present but now-lower-fasting levels of plasma insulin. 

Yes: Glucose is essential for life. Glucose is life sustaining and energy supplying. 

It is well established that glucose is always present in our blood plasma. It is recognized that “normal” glucose concentrations range from 70 to 99 milligrams per deciliter (mg/dL) at least 2-3 hours after eating and during hours of not eating or “fasting” hours.  It is also recognized that immediately after eating, our plasma glucose concentrations will normally rise only to about 130 milligrams per dL.  This reflects the “matching” insulin secretion from our pancreas that serves to transport ingested glucose into tissues for cell life functions.  This matching insulin secretion is set and will fade over two hours as the eaten glucose is transported into tissues.  

However, these same life-sustaining glucose molecules can damage cell membranes if individual molecules remain in our blood stream too long!  Oh No!

• Glucose circulates until it is transported across a cell wall into the tissue and insulin is the governor and mediator of this cellular transfer. 
• If glucose molecules are not transferred into cells within 90-120  minutes, then the glucose molecule will undergo a chemical change in the bloodstream called “oxidation.” 
• The glucose molecule, which is basically a circular structure, fractures and opens up, losing its tight circular nature (oxidation). 
• NOW, the circular glucose molecule is changed (oxidized) and it becomes ‘reactive’ with components of the exterior tissue cell walls - and with hemoglobin molecules!
• The glucose molecule becomes stuck, or attached, to various protein molecules and is now not available as an energy supplier!
• Such a reaction is random, is not controlled by any enzyme, will happen if any single glucose molecule circulates too long in the bloodstream, and is called "glycation." 
• “Glycation” is a toxic reaction. Glucose becomes stuck and cannot be released. 
• This adhesion of glucose changes the structure and function of the molecule to which it attaches, and this then perpetrates permanent tissue alterations that result in a disease state. Oh No!

Thus, glucose can be a “toxic” molecule if it is not transported into tissues promptly. Yes! But Oh No! 

Unfortunately, delayed transport of glucose into needy tissues is a common problem for millions of people world wide. This circumstance prevails in Diabetes Mellitus as well as in those individuals living in a clear Prediabetic state.  Diabetes Mellitus is defined by either an insufficient provision of insulin OR by a resistance to insulin action. Either of these abnormalities results in delayed transfer of eaten glucose into vital tissue cells and thus elevated blood glucose concentrations and prolonged circulation of any ingested glucose.  Vital cell structure injuries result because the prolonged circulation of individual glucose molecules results in their oxidation and subsequent unhealthy and undesirable attachment to various protein molecules. 

Thus Diabetes Mellitus exists as an illness if and when one’s blood glucose concentrations exceed 140-150 mg/dL either when fasting or if persisting above 150 mg/dL 2-3 hours after eating.  

Oxidized protein changes are recognized by a special blood test that analyzes hemoglobin molecules that have changed structures with accumulations of fractured glucose molecules attached.  This is regularly analyzed as “Hemoglobin A1c”.  If “Hemoglobin A1c” concentrations rise above 5.7% to 6.9% of circulating Hemoglobin, then the “Pre-Diabetic” Condition is diagnosed.  If “Hemoglobin A1c” concentrations rise above 6.9%, then overt DIabetes Mellitus is diagnosed.  

Unhealthy Consequences of Elevated Glucose and Glucose Oxidation of Proteins are:

• Slow Scarring of Blood Vessel Walls.
  • Retinal Arteries Scar and Thicken.
  • Coronary Arteries Scar and Thicken.
  • Arteries and Arterioles of Nerves Scar and Thicken.
  • Arterioles of Muscles and Skin Scar and Thicken.
• Scarring with Thickening of Arterioles Reduces Blood Flow and Causes Oxygen Insufficiency to the tissues served by those arterioles.
  • Results:
    • Retinopathy and Vision Impairment.
    • Neuropathy with Numbness and Pain.
    • Heart Disease, Heart Failure, Heart Attack.
    • Vascular Insufficiency with Muscle and Organ Failures.

A “Pre-Diabetic” State is recognized when Fasting Glucose values prevail between 100 and 130 mg/dL and Oxidized Hemoglobin A1c levels exist between 5.7% and 6.9%.

Knowing these details will help any reader who may be living with a Prediabetic State or an Actual Diabetes Mellitus diagnosis. It is possible to reduce and even eliminate “hyperglycemia” occurrences. It is possible to eliminate “Pre-Diabetes” and even overt “Diabetes”.   

• Precise and regular diet adjustments become essential. 
• Even for the non-Diabetic Person who is overweight or who has a family-history of Diabetes, diet adjustments that are informed by these facts become very important for health and disease prevention.
• And Weight Loss helps.
• And Medications help. 

These shall be subject matter of subsequent essays.

For Your Wellness,

Rex L Mahnensmith, MD