Hyperglycemia or
Hyperglycæmia, or
high blood sugar, is a condition in which an excessive amount of
glucoseGlucose is a simple sugar and an important carbohydrate in biology. Cells use it as the primary source of energy and a metabolic intermediate...
circulates in the
blood plasmaBlood plasma is the straw-colored liquid component of blood in which the blood cells in whole blood are normally suspended. It makes up about 55% of the total blood volume. It is the intravascular fluid part of extracellular fluid...
. This is generally a glucose level higher than 13.5mmol/l (243mg/dl), but symptoms may not start to become noticeable until even higher values such as 15-20 mmol/l (270-360 mg/dl). However, chronic levels exceeding 7 mmol/l (125 mg/dl) can produce organ damage.
The origin of the term is
GreekGreek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...
:
hyper-, meaning excessive;
-glyc-, meaning sweet; and
-emia, meaning "of the blood".
Definition
Glucose levels are measured in either:
- Milligrams per decilitre (mg/dl), in the United States and other countries (e.g., Japan, France, Egypt, Colombia); or
- Millimoles per litre (mmol/l), which can be acquired by dividing (mg/dl) by factor of 18.
Scientific journals are moving towards using mmol/l; some journals now use mmol/l as
the primary unit but quote mg/dl in parentheses.
Glucose levels vary before and after meals, and at various times of day; the definition of "normal" varies among medical professionals. In general, the normal range for most people (fasting adults) is about 80 to 110 mg/dl or 4 to 6 mmol/l. A subject with a consistent range above 126 mg/dl or 7 mmol/l is generally held to have hyperglycemia, whereas a consistent range below 70 mg/dl or 4 mmol/l is considered hypoglycemic. In fasting adults, blood plasma glucose should not exceed 126 mg/dL. Sustained higher levels of
blood sugarThe blood sugar concentration or blood glucose level is the amount of glucose present in the blood of a human or animal. Normally in mammals, the body maintains the blood glucose level at a reference range between about 3.6 and 5.8 mM , or 64.8 and 104.4 mg/dL...
cause damage to the blood vessels and to the organs they supply, leading to the complications of diabetes.
Chronic hyperglycemia can be measured via the HbA1c test. The definition of acute hyperglycemia varies by study, with mmol/l levels from 8 to 15.
Signs and symptoms
Temporary hyperglycemia is often benign and asymptomatic. Blood glucose levels can rise well above normal for significant periods without producing any permanent effects or symptoms. However, chronic hyperglycemia at levels more than slightly above normal can produce a very wide variety of serious complications over a period of years, including kidney damage, neurological damage, cardiovascular damage,
damage to the retinaDiabetic retinopathy is retinopathy caused by complications of diabetes mellitus, which can eventually lead to blindness....
or damage to feet and legs. Diabetic neuropathy may be a result of long-term hyperglycemia.
In diabetes mellitus (by far the most common cause of chronic hyperglycemia), treatment aims at maintaining blood glucose at a level as close to normal as possible, in order to avoid these serious long-term complications.
Acute hyperglycemia involving glucose levels that are extremely high is a medical emergency and can rapidly produce serious complications (such as fluid loss through
osmotic diuresisOsmotic diuresis is increased urination caused by the presence of certain substances in the small tubes of the kidneys. The excretion occurs when substances such as glucose enter the kidney tubules and cannot be reabsorbed...
). It is most often seen in persons who have uncontrolled insulin-dependent diabetes.
The following symptoms may be associated with acute or chronic hyperglycemia, with the first three composing the classic hyperglycemic triad:
- Polyphagia
Polyphagia means "eating too much". It derives from the Greek words πολύς which means "very much", and φαγῶ , verb for "I eat"....
- frequent hunger, especially pronounced hunger
- Polydipsia
Polydipsia is a medical symptom in which the patient displays excessive thirst. The word derives from the Greek πολυδιψία, which is derived from πολύς + δίψα...
- frequent thirst, especially excessive thirst
- Polyuria
Polyuria is a condition usually defined as excessive or abnormally large production or passage of urine . Frequent urination is sometimes included by definition, but is nonetheless usually an accompanying symptom...
- frequent urination
- Blurred vision
-Causes:There are many causes of blurred vision:* Use of atropine or other anticholinergics* Presbyopia -- Difficulty focusing on objects that are close. The elderly are common victims....
- Fatigue
Fatigue is a state of awareness describing a range of afflictions, usually associated with physical and/or mental weakness, though varying from a general state of lethargy to a specific work-induced burning sensation within one's muscles...
(sleepiness).
- Weight loss
Weight loss, in the context of medicine, health or physical fitness, is a reduction of the total body mass, due to a mean loss of fluid, body fat or adipose tissue and/or lean mass, namely bone mineral deposits, muscle, tendon and other connective tissue...
- Poor wound
A wound is a type of injury in which skin is torn, cut or punctured , or where blunt force trauma causes a contusion . In pathology, it specifically refers to a sharp injury which damages the dermis of the skin.-Open:...
healing (cuts, scrapes, etc.)
- Dry mouth
- Dry or itchy skin
-Dermis:The dermis is the layer of skin beneath the epidermis that consists of connective tissue and cushions the body from stress and strain. The dermis is tightly connected to the epidermis by a basement membrane. It also harbors many Mechanoreceptors that provide the sense of touch and heat...
- Tingling in feet or heels
- Erectile dysfunction
Erectile dysfunction is sexual dysfunction characterized by the inability to develop or maintain an erection of the penis during sexual performance....
- Recurrent infection
An infection is the colonization of a host organism by parasite species. Infecting parasites seek to use the host's resources to reproduce, often resulting in disease...
s, external ear infections (swimmer's earOtitis externa is an inflammation of the outer ear and ear canal. Along with otitis media, external otitis is one of the two human conditions commonly called "earache". It also occurs in many other species. Inflammation of the skin of the ear canal is the essence of this disorder...
)
- Cardiac arrhythmia
- Stupor
Stupor is the lack of critical cognitive function and level of consciousness wherein a sufferer is almost entirely unresponsive and only responds to base stimuli such as pain. This is often mistaken for delirium and treated with Haldol and or other anti-psychotic drugs...
- Coma
In medicine, a coma is a state of unconsciousness, lasting more than 6 hours in which a person cannot be awakened, fails to respond normally to painful stimuli, light or sound, lacks a normal sleep-wake cycle and does not initiate voluntary actions. A person in a state of coma is described as...
Frequent hunger without other symptoms can also indicate that blood sugar levels are too low. This may occur when people who have diabetes take too much oral hypoglycemic medication or insulin for the amount of food they eat. The resulting drop in blood sugar level to below the normal range prompts a hunger response. This hunger is not usually as pronounced as in Type I diabetes, especially the juvenile onset form, but it makes the prescription of oral hypoglycemic medication difficult to manage.
Polydipsia and polyuria occur when blood glucose levels rise high enough to result in excretion of excess glucose via the kidneys (
glycosuriaGlycosuria or glucosuria is the excretion of glucose into the urine. Ordinarily, urine contains no glucose because the kidneys are able to reclaim all of the filtered glucose back into the bloodstream. Glycosuria is nearly always caused by elevated blood glucose levels, most commonly due to...
), producing osmotic
diuresisDiuresis may refer to:* Urine production, as an aspect of fluid balance* Excessive urine production - see polyuria* Immersion diuresis...
.
Symptoms of
Diabetic KetoacidosisDiabetic ketoacidosis is a potentially life-threatening complication in patients with diabetes mellitus. It happens predominantly in those with type 1 diabetes, but it can occur in those with type 2 diabetes under certain circumstances...
may include:
- Ketoacidosis
Ketoacidosis is a metabolic state associated with high concentrations of ketone bodies, formed by the breakdown of fatty acids and the deamination of amino acids. The two common ketones produced in humans are acetoacetic acid and β-hydroxybutyrate....
- Kussmaul hyperventilation: deep, rapid breathing
- Confusion or a decreased level of consciousness
- Dehydration due to glycosuria
Glycosuria or glucosuria is the excretion of glucose into the urine. Ordinarily, urine contains no glucose because the kidneys are able to reclaim all of the filtered glucose back into the bloodstream. Glycosuria is nearly always caused by elevated blood glucose levels, most commonly due to...
and osmotic diuresis
- Acute hunger and/or thirst
- 'Fruity' smelling breath odor
- Impairment of cognitive function, along with increased sadness and anxiety
Diabetes mellitus
Chronic hyperglycemia that persists even in fasting states is most commonly caused by
diabetes mellitusDiabetes mellitus, often simply referred to as diabetes, is a group of metabolic diseases in which a person has high blood sugar, either because the body does not produce enough insulin, or because cells do not respond to the insulin that is produced...
, and in fact chronic hyperglycemia is the defining characteristic of the disease. Intermittent hyperglycemia may be present in prediabetic states. Acute episodes of hyperglycemia without an obvious cause may indicate developing diabetes or a predisposition to the disorder.
In diabetes mellitus, hyperglycemia is usually caused by low
insulinInsulin is a hormone central to regulating carbohydrate and fat metabolism in the body. Insulin causes cells in the liver, muscle, and fat tissue to take up glucose from the blood, storing it as glycogen in the liver and muscle....
levels (
Diabetes mellitus type 1Diabetes mellitus type 1 is a form of diabetes mellitus that results from autoimmune destruction of insulin-producing beta cells of the pancreas. The subsequent lack of insulin leads to increased blood and urine glucose...
) and/or by resistance to insulin at the cellular level (
Diabetes mellitus type 2Diabetes mellitus type 2formerly non-insulin-dependent diabetes mellitus or adult-onset diabetesis a metabolic disorder that is characterized by high blood glucose in the context of insulin resistance and relative insulin deficiency. Diabetes is often initially managed by increasing exercise and...
), depending on the type and state of the disease. Low insulin levels and/or insulin resistance prevent the body from converting glucose into
glycogenGlycogen is a molecule that serves as the secondary long-term energy storage in animal and fungal cells, with the primary energy stores being held in adipose tissue...
(a starch-like source of energy stored mostly in the liver), which in turn makes it difficult or impossible to remove excess glucose from the blood. With normal glucose levels, the total amount of glucose in the blood at any given moment is only enough to provide energy to the body for 20-30 minutes, and so glucose levels must be precisely maintained by the body's internal control mechanisms. When the mechanisms fail in a way that allows glucose to rise to abnormal levels, hyperglycemia is the result.
Drugs
Certain medications increase the risk of hyperglycemia, including corticosteroids,
octreotideOctreotide is an octapeptide that mimics natural somatostatin pharmacologically, though it is a more potent inhibitor of growth hormone, glucagon, and insulin than the natural hormone...
,
beta blockerBeta blockers or beta-adrenergic blocking agents, beta-adrenergic antagonists, beta-adrenoreceptor antagonists or beta antagonists, are a class of drugs used for various indications. They are particularly for the management of cardiac arrhythmias, cardioprotection after myocardial infarction ,...
s,
epinephrineEpinephrine is a hormone and a neurotransmitter. It increases heart rate, constricts blood vessels, dilates air passages and participates in the fight-or-flight response of the sympathetic nervous system. In chemical terms, adrenaline is one of a group of monoamines called the catecholamines...
,
thiazideThiazide is a term used to describe a type of molecule and a class of diuretics often used to treat hypertension and edema ....
diureticA diuretic provides a means of forced diuresis which elevates the rate of urination. There are several categories of diuretics. All diuretics increase the excretion of water from bodies, although each class does so in a distinct way.- Medical uses :...
s,
niacin"Niacin" redirects here. For the neo-fusion band, see Niacin .Niacin is an organic compound with the formula and, depending on the definition used, one of the forty to eighty essential human nutrients.Niacin is one of five vitamins associated with a pandemic deficiency disease: niacin deficiency...
,
pentamidinePentamidine is an antimicrobial medication given for prevention and treatment of Pneumocystis pneumonia caused by Pneumocystis jirovecii , a severe interstitial type of pneumonia often seen in patients with HIV infection...
, protease inhibitors, L-asparaginase, and some
antipsychoticAn antipsychotic is a tranquilizing psychiatric medication primarily used to manage psychosis , particularly in schizophrenia and bipolar disorder. A first generation of antipsychotics, known as typical antipsychotics, was discovered in the 1950s...
agents. The acute administration of stimulants such as
amphetamineAmphetamine or amfetamine is a psychostimulant drug of the phenethylamine class which produces increased wakefulness and focus in association with decreased fatigue and appetite.Brand names of medications that contain, or metabolize into, amphetamine include Adderall, Dexedrine, Dextrostat,...
typically produces hyperglycemia; chronic use, however, produces
hypoglycemiaHypoglycemia or hypoglycæmia is the medical term for a state produced by a lower than normal level of blood glucose. The term literally means "under-sweet blood"...
. Some of the newer psychotropic medications such as Zyprexa (Olanzapine), and Cymbalta (Duloxetine), can also cause significant hyperglycemia.
Critical illness
A high proportion of patients suffering an acute stress such as
strokeA stroke, previously known medically as a cerebrovascular accident , is the rapidly developing loss of brain function due to disturbance in the blood supply to the brain. This can be due to ischemia caused by blockage , or a hemorrhage...
or
myocardial infarctionMyocardial infarction or acute myocardial infarction , commonly known as a heart attack, results from the interruption of blood supply to a part of the heart, causing heart cells to die...
may develop hyperglycemia, even in the absence of a diagnosis of diabetes. Human and animal studies suggest that this is not benign, and that stress-induced hyperglycemia is associated with a high risk of mortality after both stroke and myocardial infarction.
Plasma glucose >120 mg/dl in the absence of diabetes is a clinical sign of
sepsisSepsis is a potentially deadly medical condition that is characterized by a whole-body inflammatory state and the presence of a known or suspected infection. The body may develop this inflammatory response by the immune system to microbes in the blood, urine, lungs, skin, or other tissues...
.
Physical traumaTrauma refers to "a body wound or shock produced by sudden physical injury, as from violence or accident." It can also be described as "a physical wound or injury, such as a fracture or blow." Major trauma can result in secondary complications such as circulatory shock, respiratory failure and death...
,
surgerySurgery is an ancient medical specialty that uses operative manual and instrumental techniques on a patient to investigate and/or treat a pathological condition such as disease or injury, or to help improve bodily function or appearance.An act of performing surgery may be called a surgical...
and many forms of severe stress can temporarily increase glucose levels.
Physiological stress
Hyperglycemia occurs naturally during times of
infectionAn infection is the colonization of a host organism by parasite species. Infecting parasites seek to use the host's resources to reproduce, often resulting in disease...
and
inflammationInflammation is part of the complex biological response of vascular tissues to harmful stimuli, such as pathogens, damaged cells, or irritants. Inflammation is a protective attempt by the organism to remove the injurious stimuli and to initiate the healing process...
. When the body is stressed, endogenous catecholamines are released that - amongst other things - serve to raise the blood glucose levels. The amount of increase varies from person to person and from inflammatory response to response. As such, no patient with first-time hyperglycemia should be diagnosed immediately with diabetes if that patient is concomitantly ill with something else. Further testing, such as a
fastingFasting is primarily the act of willingly abstaining from some or all food, drink, or both, for a period of time. An absolute fast is normally defined as abstinence from all food and liquid for a defined period, usually a single day , or several days. Other fasts may be only partially restrictive,...
plasma glucose, random plasma glucose, or two-hour
postprandialPostprandial means after eating a meal while preprandial is before a meal.-Usages of the term:This term is used in many contexts but also in relation to blood sugar levels, which are normally measured 2 hours after and before eating in a postprandial glucose test...
plasma glucose level, must be performed.
Treatment
Treatment of hyperglycemia requires elimination of the underlying cause,
e.g., treatment of diabetes when diabetes is the cause. Acute hyperglycemia can be treated by direct administration of insulin in most cases. Severe hyperglycemia can be treated with oral hypoglycemic therapy and lifestyle modification.
Complications
Hyperglycemia can be a serious problem if not treated in time. In untreated hyperglycemia, a condition called
ketoacidosisKetoacidosis is a metabolic state associated with high concentrations of ketone bodies, formed by the breakdown of fatty acids and the deamination of amino acids. The two common ketones produced in humans are acetoacetic acid and β-hydroxybutyrate....
could occur. Ketoacidosis develops when the body does not have enough
insulinInsulin is a hormone central to regulating carbohydrate and fat metabolism in the body. Insulin causes cells in the liver, muscle, and fat tissue to take up glucose from the blood, storing it as glycogen in the liver and muscle....
. Without insulin, the body isn't able to utilize the glucose for fuel, so the body starts to break down fats for energy.
When the body breaks down fats, it produces a waste product called ketones. The body cannot tolerate large quantity of ketones and will try to remove it through the urine. Unfortunately, the body is not able to remove all the ketones and thus they build up in the blood stream, which can lead to ketoacidosis.
Ketoacidosis is life-threatening condition which needs immediate treatment. Symptoms include: shortness of breath, breath that smells fruity(such as pear drops), nausea and vomiting, and very dry mouth.
External links
- Hyperglycemia information - from the American Diabetes Association
The American Diabetes Association is a United States-based association working to fight the consequences of diabetes, and to help those affected by diabetes...
- Hyperglycemia in infants - from MedlinePlus
MedlinePlus is a free Web site that provides consumer health information for patients, families, and Health care providers. The site brings together information from the United States National Library of Medicine, the National Institutes of Health , other U.S. government agencies, and...
- Hyperglycemia affects brain Hemichorea/Hemiballismus