Diabetes mellitus always features elevated blood glucose concentrations. Elevated blood glucose leads to glucose spillage in the urine with associated loss of water, salt and potassium from the diuretic effect of glucose in the urine. Vascular dehydration, lower blood pressure, weakness, and eventual collapse results.
Elevated blood glucose also causes tissue dehydration. Tissue water shifts from inside the cells of tissues to the blood stream because of a strong “osmotic” effect that glucose exerts on cell water when glucose concentrations are high in the blood stream but not high inside the cells of tissues. Water is drawn out of cells and then this water is rapidly excreted by the diuretic effect of high glucose in urine. The cells of vital tissues can suffer injury from this effect. Cells compensate by generating compounds that serve to trap or hold water and prevent the osmotic draw out. Nevertheless, cells do shrink and suffer from prolonged hyperglycemia.
Glucose molecules that do not promptly enter a cell to provide fuel and energy continue to circulate in the blood. Diabetes mellitus thus features elevated blood glucose as its central problem.
Besides tissue water losses and vascular salt and water and potassium losses, persistent glucose above normal in the blood stream leads to harmful secondary reactions. These reactions are called “glycation” reactions and this reaction simply features the attachment of a glucose molecule to a cell membrane or other large molecule, thus changing the basic nature of that glycated molecule.
Glycation is the real hazard of diabetes mellitus. Circulating glucose molecules will glycate capillary walls of any organ. We worry about glycation of the retina. This certainly happens. We worry about glycation of heart muscle and coronary arteries. This certainly happens. We worry about glycation of brain cells and nerve cells. This certainly happens. Each glycation event changes the nature of the now-glycated molecule. Each glycation event thus alters structure and function of the glycated tissue.
The care of the person who has diabetes mellitus thus focuses on preventing glycation events. Prevention of glycation events requires consistent normalization of blood glucose concentrations.
Blood glucose concentrations should reside below 100 mg/dL during fasting time periods. Fasting means abstaining from food and caloric beverage for at least 8 hours. If fasting blood glucose values exceed 125 mg/dL, then diabetes mellitus exists. The goal for fasting blood glucose in persons with diabetes mellitus is below 125 mg/dL.
After eating, blood glucose concentrations normally increase slightly. In non-diabetic individuals, the rise in blood glucose after eating should not exceed 140 mg/dL. As glucose enters our blood stream from food or beverage, our pancreas should release a proportional amount of insulin, which serves to transport new glucose from the blood stream into tissues for either immediate or eventual energy.
The person with diabetes mellitus will exhibit a surge in blood glucose after food or beverage ingestion that exceeds 140 mg/dL. For the person who knows that they are afflicted with diabetes, the proper goal is to prevent their glucose levels after eating from rising above 180 mg/dL. One may ask “why 180 mg/dL?” “Why not 140 mg/dL?” This is a very good question.
The explanation resides with the observation that deliberate control of glucose elevations with medication can be too extreme and cause below-normal blood glucose values. Thus, formal Diabetes Management Guidelines provide targets judged to be safe as well as effective.
A third parameter is tracked routinely: glycated hemoglobin. Hemoglobin that resides in our red blood cells is one of the molecules that reacts with circulating glucose and becomes glycated. Hence, glycated hemoglobin values measured from routine blood samples indicate “quality” of control of blood glucose from the medications prescribed along with diet adjustments. The goal for glycated hemoglobin is less than 7% for the usual young person and usual adult. For feeble elderly and other select persons with serious kidney disease and cerebrovascular disease, the goal for glycated hemoglobin is 7-8%. The caution is to avoid inducing very low blood glucose concentrations with medication, which can result in harm.
Thus, Personal Goals for Diabetes Mellitus are:
- Fasting glucose less than 130 mg/dL.
- After eating glucose less than 180 mg/dL.
- Glycated hemoglobin less than 7%, unless advised by your physician to aim for 8%.
- Harmony is essential: harmony between food quantity, food type, carbohydrate quantities, fat quantities, AND any and all medications prescribed. Harm and hazard strikes when best harmony is not achieved or sustained AND glucose concentrations thus fluctuate widely.
Rex Mahnensmith, MD is a practicing physician who serves as a General Internist in the practice of Primary Care for all individuals who elect health care. He has long served in educational roles as well as in direct patient care roles. Now he devotes his time and talents to the devoted care of individuals. He is especially interested in preventative medicine, health maintenance, wellness, and healthy choices for living. He serves individuals with chronic illnesses as well as those with no illness. He aims to help individuals to know and to make healthy choices in all circumstances. The devoted care of individuals with diabetes mellitus, nutritional disorders, hypertension, kidney diseases, asthma, and other chronic illnesses is a special calling for Dr.Mahnensmith. But it is not the disease which calls is special care, it is the person. His calling is to serve and to serve well.