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Encyclopedia > Blood sugar

In medicine, blood sugar is a term used to refer to levels of glucose in the blood. Blood sugar concentration, or serum glucose level, is tightly regulated in the human body. Glucose, transported via the bloodstream, is the primary source of energy for the body's cells. medicines, see medication and pharmacology. ... Glucose (Glc), a monosaccharide (or simple sugar), is the most important carbohydrate in biology. ... Human blood smear: a - erythrocytes; b - neutrophil; c - eosinophil; d - lymphocyte. ...


Normally, blood glucose levels stay within narrow limits throughout the day: 4 to 8 mmol/L (70 to 150 mg/dL), thus the total amount of glucose in the bloodstream is 3.3 to 7g (5L blood estimated). Levels rise after meals and are usually lowest in the morning, before the first meal of the day.


Diabetes mellitus is the most prominent disease related to failure of blood sugar regulation. For the disease characterized by excretion of large amounts of very dilute urine, see diabetes insipidus. ... Glucose Blood sugar regulation is the process by which the levels of blood sugar, primarily glucose, are maintained by the body. ...


Though it is called "blood sugar", other sugars besides glucose are found in the blood, like fructose and galactose. However, only glucose levels are regulated via insulin and glucagon. Fructose (or levulose) is a simple sugar (monosaccharide) found in many foods and is one of the three most important blood sugars along with glucose and galactose. ... Galactose (also called brain sugar) is a type of sugar found in dairy products, in sugar beets and other gums and mucilages. ... Insulin (from Latin insula, island, as it is produced in the Islets of Langerhans in the pancreas) is a polypeptide hormone that regulates carbohydrate metabolism. ... Glucagon ball and stick model A microscopic image stained for glucagon. ...

Contents

Glucose Measurement

Sample Type

Historically, blood glucose values were given in terms of whole blood, but most laboratories now measure the serum glucose levels. Because RBC (erythrocytes) have a higher concentration of protein (i.e. hemoglobin) than serum, serum has a higher water content and consequently more dissolved glucose than does whole blood. To convert from whole-blood glucose, multiply the value by 1.15 to give the serum/plasma level. Look up Serum in Wiktionary, the free dictionary. ... RBC most frequently refers to: Royal Bank of Canada, which uses RBC as its master brand Red blood cell, used in biology Risk-based capital, referring to financial institution regulation RBC Ministries, a Christian organization founded by Dr. M. R. De Haan And can also mean: Rasu Baptist Church Real... Human red blood cells Red blood cells are the most common type of blood cell and are the vertebrate bodys principal means of delivering oxygen to body tissues via the blood. ...


Collection of blood in clot (red-top) tubes for serum chemistry analysis permits the metabolism of glucose in the sample by blood cells until separated by centrifugation. Very high WBC counts can lead to excessive glycolysis in the sample with substantial reduction of glucose level. Ambient temperature at which the blood sample is kept prior to centrifugation and separation of Plasma/Serum also affects glucose levels. At refrigerator temperatures, glucose remains relatively stable for several hours in the blood sample. At room temperature (25°C), a loss of 1 to 2% of glucose per hour should be expected. The loss of glucose levels in aforementioned conditions can be prevented by using Fluoride top (gray-top) as the anticoagulant of choice upon blood collection, as Fluoride inhibits glycolysis. However, this should only be used when blood will be transported from one hospital laboratory to another for glucose measurement. Red-top serum separator tubes also preserve glucose in samples once they have been centrifugated to isolate the serum from cells, this tube would be the most efficient. Particular care should be given to drawing blood samples from the arm opposite the one in which an intravenous line is inserted, to prevent contamination of the sample with intravenous fluids (IV). Alternatively, blood can be drawn from the same arm with an IV line after the IV was turned off for at least 5 minutes and the arm is elevated to drain the infused fluids away from the vein. As little as 10% contamination with 5% dextrose (D5W) will elevate glucose in a sample by 500mg/dl or more. Arterial, capillary and venous blood have comparable glucose levels in a fasting individual, whereas after meals venous levels are lower than capillary or arterial blood. Centrifugation is a process that involves the use of the centrifugal force for the separation of mixtures. ... WBC is a three-letter abbreviation with multiple meanings, as described below: White blood cell World Boxing Council The WBC, a music group Westboro Baptist Church Wilkes-Barre Connecting Railroad White Blood Cells (album) Washington Bible College Widcombe Baptist Church World Baseball Classic World Boardgaming Championships Womens Business Council... Overview of glycolysis. ... An intravenous drip in a hospital Intravenous therapy or IV therapy is the administration of liquid substances directly into a vein. ... A space-filling model of glucose Glucose, a simple monosaccharide sugar, is one of the most important carbohydrates and is used as a source of energy in animals and plants. ...


Methodology

There are two different major methods that have been used to measure glucose. The older one is a chemical method that exploits the nonspecific reducing property of glucose in a reaction with an indicator substance that acquires or changes color on its reduction. Since other blood compounds also have reducing properties (e.g., urea, which can build up in uremic patients), this method can have erroneous measurements up to 5 to 15 mg/dl. This is solved by the Enzymatic methods that are highly specific for glucose. The two most common employed enzyme is glucose oxidase and hexokinase. The glucose oxidase enzyme (GOx) (EC 1. ... A hexokinase is an enzyme that phosphorylates a six-carbon sugar, a hexose, to a hexose phosphate. ...

I. CHEMICAL METHODS
A. Oxidation-Reduction Reaction
Glucose + Alkaline Copper Tartarate&# 0;ghtarrow{Reduction} Cuprous Oxide
1. Alkaline Copper Reduction
Folin Wu Method Cu^{++} + Phosphomolybdic Acid&# 0;ghtarrow{Oxidation} Phosphomolybdenum Oxide Blue end-product
Benedict's method
  • Modification of Folin wu for Qualitative Urine Glucose
Nelson Somoygi Method Cu^{++} + Arsenomolybdic Acid&# 0;ghtarrow{Oxidation} Arsenomolybdenum Oxide Blue end-product
Neocuproine Method Cu^{++} + Neocuproine&# 0;ghtarrow{Oxidation} Cu^{++} Neocuproine Complex* Yellow-orange color Neocuproine
Shaeffer Hartmann Somygi
  • Utilizes the principle of Iodine reaction with Cuprous byproduct.
  • Excess I2 is then titrated with thiosulfate.
2. Alkaline Ferricyanide Reduction
Hagedorn Jensen Glucose + Alk. Ferricyanide Yellowlongrightarrow Ferrocyanide Colorless end product; other reducing substances interfere with reaction
B. Condensation
Orht-touidine Method
Anthrone (Phenols) Method
  • Forms hydroxymethyl furfural in hot acetic acid
II. ENZYMATIC METHODS
A. Glucose Oxidase
Glucose + O^{2}&# 0;ghtarrow[Oxidation] {glucose oxidase}Cuprous Oxide
Saifer Gernstenfield Method H^{2}O_2 + O-dianisidine&# 0;ghtarrow[Oxidation] {peroxidase} H_2O + oxidized chromogen Inhibited by reducing substances like BUA, Bilirubin, Glutathione, Ascorbic Acid
Trinder Method
  • uses 4-aminophenazone oxidatively coupled with Phenol
  • Subject to less interference by increases serum levels of Creatinine, Uric Acid or Hemoglobin
  • Inhibited by Catalase
Kodak Ektachem
  • A Dry Chemistry Method
  • Uses Reflectance Spectrophotometry to measure the intensity of color through a lower transparent film
Glucometer
  • Home monitoring blood glucose assay method
  • Uses a strip impregnated with a Glucose Oxidase reagent
B. Hexokinase

begin{alignat}{2} & Glucose + ATP&# 0;ghtarrow[Phosphorylation] {Hexokinase + Mg^{++}} G-6PO_4 + ADP  & G-6PO_4 + NADP&# 0;ghtarrow[Oxidation] {G-6PD} G-Phosphogluconate + NADPH + H^{+}  end{alignat} General Name, Symbol, Number iodine, I, 53 Chemical series halogens Group, Period, Block 17, 5, p Appearance violet-dark gray, lustrous Standard atomic weight 126. ... It has been suggested that thiosulfate ion be merged into this article or section. ... An aromatic amine is an amine with an aromatic substituent - that is -NH2, -NH- or nitrogen group(s) attached to an aromatic hydrocarbon, whose structure usually contains one or more benzene rings. ... Acetic acid, also known as ethanoic acid, is an organic chemical compound best recognized for giving vinegar its sour taste and pungent smell. ... Glycosylamine is a compound consisting of an amine with a β-N-glycosidic bond to a carbohydrate. ... Bilirubin is a yellow breakdown product of heme catabolism. ... Skeletal formula of glutathione 3D model of glutathione Glutathione (GSH), whose IUPAC name is 2-amino-5-{[2-[(carboxymethyl)amino]- 1-(mercaptomethyl)-2-oxoethyl]amino}-5-oxopentanoic acid, is γ-glutamylcysteinylglycine, a tripeptide. ... This article deals with the molecular aspects of ascorbic acid. ... Chemical structure of creatinine. ... This article or section is in need of attention from an expert on the subject. ... 3-dimensional structure of hemoglobin. ... Catalase (human erythrocyte catalase: PDB 1DGF, EC 1. ...

  • NADP as cofactor
  • NADPH (reduced product) is measured in 340 nm
  • More specific than Glucose Oxidase method due to G-6PO_4, which inhibits interfering substances except when sample is hemolyzed

Nicotinamide adenine dinucleotide (NAD+) Nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP) are two important coenzymes found in cells. ...

Laboratory Tests Commonly Employed

  1. Fasting Blood Sugar or Glucose test (FBS)
  2. Urine Glucose test
  3. Two-hr Postprandial Blood Sugar Test (2-h PPBS)
  4. Oral Glucose Tolerance test (OGTT)
  5. Intravenous Glucose Tolerance test (IVGTT)
  6. Glycosylated Hemoglobin (HbA1C)
  7. Self-monitoring of Glucose level via Home Kits

Clinical Correlation

The Fasting blood glucose (FBG) level gives the best indication of overall glucose homeostasis, and most routine determinations should be done on fasting samples. Conditions that affect glucose levels are shown in the table below. They reflect the abnormalities in the multiple control mechanism of glucose regulation.


The metabolic response to a carbohydrate challenge is conveniently assessed by the postprandial glucose level drawn 2 hours after a meal or a glucose load. In addition, the glucose tolerance test, consisting of serial timed measurements after a standardized amount of oral glucose intake, is used to aid in the diagnosis of Diabetes. This article is about the disease that features high blood sugar. ...

Causes of Abnormal Glucose Levels
Persistent Hyperglycemia Transient Hyperglycemia Persistent Hypoglycemia Transient Hypoglycemia
Reference Range, FBG: 70-110 mg/dl
Diabetes Mellitus Pheochromocytoma Insulinoma Acute Alcohol Ingestion
Adrenal cortical hyperactivity Cushing's Syndrome Severe Liver Disease Adrenal cortical insufficiency Addison's Disease Drugs: salicylates, antituberculosis agents
Hyperthyroidism Acute stress reaction Hypopituitarism Severe Liver disease
Acromegaly Shock Galactosemia Several Glycogen storage diseases
Obesity Convulsions Ectopic Insulin production from tumors Hereditary fructose intolerance

A pheochromocytoma (also phaeochromocytoma, English spelling) is a tumor of the medulla of the adrenal glands originating in the chromaffin cells, which secretes excessive amounts of catecholamines, usually epinephrine and norepinephrine. ... An insulinoma is a tumour of the pancreas derived from the beta cells which while retaining the ability to synthesize and secrete insulin is autonomous of the normal feedback mechanisms. ... The liver is an organ in vertebrates including humans. ... Addisons disease (also known as chronic adrenal insufficiency, or hypocortisolism) is a rare endocrine disorder which results in the body not producing sufficient amounts of certain adrenal hormones. ... Salicylic acid is a colorless, crystalline organic carboxylic acid. ... Hyperthyroidism (or overactive thyroid gland) is the clinical syndrome caused by an excess of circulating free thyroxine (T4) or free triiodothyronine (T3), or both. ... Hypopituitarism is a medical term describing deficiency (hypo) of one or more hormones of the pituitary gland. ... Acromegaly (from Greek akros high and megas large - extremities enlargement) is a hormonal disorder that results when the pituitary gland produces excess growth hormone (hGH). ... This article is about the medical condition. ... Galactosemia is a rare genetic metabolic disorder which affects an individuals ability to properly digest the sugar galactose. ... Glycogen storage disease (synonyms: glycogenosis, dextrinosis) is any one of several inborn errors of metabolism that result from enzyme defects that affect the processing of glycogen synthesis or breakdown within muscles, liver, and other cell types. ... This article is about the medical condition. ...

Direct health effects of blood sugar problems

If blood sugar levels drop too low, a potentially fatal condition called hypoglycemia develops. Symptoms may include lethargy, impaired mental functioning, irritability, and loss of consciousness. Hypoglycemia (hypoglycæmia in the UK) is a medical term referring to a pathologic state produced by a lower than normal amount of sugar (glucose) in the blood. ... Fatigue is a feeling of excessive tiredness or lethargy, with a desire to rest, perhaps to sleep. ... Irritability is an excessive response to stimuli. ... Unconsciousness is the absence of consciousness. ...


If levels remain too high, appetite is suppressed over the short term. Long-term hyperglycemia causes many of the long-term health problems associated with diabetes, including eye, kidney, and nerve damage. Hyperglycemia or High Blood Sugar is a condition in which an excessive amount of glucose circulates in the blood plasma. ... This article is about the disease that features high blood sugar. ...


Low blood sugar

Some people report drowsiness or impaired cognitive function several hours after meals, which they believe is related to a drop in blood sugar, or "low blood sugar". For more information, see:

Idiopathic postprandial syndrome is a medical term describing a collection of symptoms popularly attributed to hypoglycemia but without demonstrably low glucose levels. ... Hypoglycemia (hypoglycæmia in the UK) is a medical term referring to a pathologic state produced by a lower than normal amount of sugar (glucose) in the blood. ...

Convert to your local units used: mg/dl or mmol/L

Countries that use the metric system use mmol/L. The U.S. uses mg/dL.
To convert Blood Glucose readings:-
Divide the mg/dL by 18 to get mmol/L (or multiply by 0.055).
Multiply the mmol/L by 18 to get mg/dL (or divide with 0.055).


External links

References

  • John Bernard Henry, M.D.: Clinical diagnosis and Management by Laboratory Methods 20th edition, Saunders, Philadelphia, PA, 2001.
  • Ronald A. Sacher and Richard A. McPherson: Widmann's Clinical Interpretation of Laboratory Tests 11th edition, F.A. Davis Company, 2001.

  Results from FactBites:
 
Blood Sugar (401 words)
Blood sugar is measured in milligrams of glucose per 100 milliliters of blood.
Blood sugar levels are effected by eating too much, eating the wrong foods, a lack of physical activity, stress, medication, or by infection and illness.
Table sugar and other carbohydrates can elevate blood sugar to unhealthy levels or cause reactions to the insulin that is subsequently produced.
Blood sugar tests: Understanding your results - MayoClinic.com (893 words)
A fasting blood sugar level of 126 mg/dL or higher is consistent with either type 1 or type 2 diabetes when accompanied by classic signs and symptoms of diabetes — increased thirst or hunger, frequent urination, weight loss or blurred vision.
If your blood sugar level is higher than 200 mg/dL and you have signs or symptoms of diabetes, you may be diagnosed with diabetes without a second test for confirmation.
If your random blood sugar level is higher than 140 mg/dL but lower than 200 mg/dL, you may have prediabetes.
  More results at FactBites »

 
 

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