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Diabetes is a disease in which
the body does not produce or properly use insulin. According to
the American Diabetes Association, 20.8 million people in the United
States, or seven percent of the population, have diabetes. About1.5
million new cases were diagnosed in people aged 20 years or older
in 2005. The World Health Organization (WHO) recently compiled data
that estimates that, worldwide,180 million people have diabetes,
and that number is expected to double by 2030. Diabetes is no longer
mainly a disease of the aged; increasingly, more young people are
diagnosed with diabetes due to rampant obesity. Diabetes is the
next great lifestyle disease pandemic. One out of every ten health
care dollars spent in the United States goes to treat diabetic patients.
It is estimated that, in 2002, diabetes care cost a total of $132
billion, of which $92 billion was spent on direct medical costs
and $40 billion on indirect costs, such as disability payments,
loss of work income, and premature mortality. Health care costs
for a person with diabetes in the US are three times more than the
health care costs of a healthy non-diabetic.
Since 1922 and its discovery by Canadian doctors Banting and Best,
the use of subcutaneous insulin injections has been the most important
treatment for diabetes. However, its use is often associated with
lack of compliance, due to the pain associated with multiple daily
injections. Hence, there is a big demand for an insulin delivery
system that can be administered without painful shots. Development
of such an insulin delivery system promises a multibillion dollar
market and greater patient compliance. Below, we look at diabetes
in general, then discuss the dangers of new methods of self-administering
insulin: inhalation insulin, nasal and oral spray insulin, oral
insulin, and insulin suppositories.
Diabetes is a life-long, life-threatening chronic disease marked
by high levels of sugar in the blood. The pancreatic endocrine gland,
which produces insulin, and cells that use insulin for the uptake
of glucose from blood are at the root of this life-threatening pandemic.
All racial groups are affected. People with diabetes have high blood
sugar because their pancreas does not make enough insulin or because
their muscle, fat, liver, and other body cells do not respond to
blood insulin (insulin resistance) as do those of healthy non-diabetics.
Diabetes, then, is caused by too little or no insulin produced in
the pancreas, cell resistance to the biologic effects of insulin,
or both.1,2 To understand diabetes, it is important to
understand the normal process of food metabolism. Several things
happen when food is digested:
1. After food is digested, sugar (glucose)
enters the bloodstream from the intestines. Glucose is a source
of fuel for the body, producing energy in cells for all bodily
2. The pancreas makes insulin in its endocrine gland (islets of
Langerhans) in response to a blood sugar rise after meal. The
role of insulin is to move glucose from the bloodstream into muscle,
fat, and liver cells, where it can be used as fuel for immediate
energy needs and/or stored as glycogen (mainly in the liver) to
be released for energy between meals as needed when the blood
Types of Diabetes
· Type 1 diabetes results from selective beta cell destruction
in the islets, which results in severe or absolute natural insulin
production deficiency. Type 1 diabetes is known as juvenile diabetes,
afflicts children, comprises less than ten percent of total diabetic
cases, and is a lifelong condition. It is an autoimmune disease
in which the immune system attacks and kills insulin-producing cells.
Repeated daily injections of insulin are needed to sustain life
and prevent life-threatening raise of blood sugar. At any given
time, the entire human pancreas contains up to 8 mg of insulin,
representing approximately 200 biologic units not found in the pancreas
of type 1 diabetics.
· Type 2 diabetes is more common than type 1, comprising
more than 90% of cases of diabetes, and usually occurs in adults.
Increasing obesity from overeating and failure to exercise are important
predisposing risk factors. Conventionally, type 2 diabetes is viewed
as high blood sugar (hyperglycemia) as a primary disease caused
by an etiologically uncertain combination of obesity-associated
insulin resistance with gradual reduction in insulin production
due to the gradual loss of beta cells that produce insulin. The
latest research points to the novel "lipocentric" theory,
which states that high blood sugar (hyperglycemia) associated with
type 2 diabetics, insulin resistance, and beta cell loss is secondary
to the metabolic trauma caused by outside (ectopic) lipid (fat)
deposition or fat toxicity (lipotoxicity) due to excess caloric
intake.3-5 Fat is at the center of the cause for this
condition (i.e., lipocentric). It is interesting to note that the
studies by Dixon et al. and Unger provide support for the "lipocentric"
hypothesis by demonstrating that the weight loss that follows gastric
banding in morbidly obese is accompanied by remission of diabetes
in 73% of obese patients with type 2 diabetes. This finding supports
45 years of biochemical, physiological, and clinical research pointing
to lipid overload as the underlying cause of this disease.3
A molecular pathway to insulin resistance seems to be due to outside
(ectopic) accumulation of unoxidized fatty acids. Surplus lipids
arising from overeating are in fact the link between obesity, hyperglycemia,
and insulin resistance.4 In 1994, Lee et al. demonstrated
that outside (ectopic) lipids that accumulate in pancreatic insulin-producing
islets parallel with other tissues lipid deposits can cause the
subtotal lipotoxic destruction of insulin-producing beta cells that
precipitates the hyperglycemia, thereby providing the final evidence
for the lipocentric theory of type 2 diabetes.5 Other
studies point out that the root cause of insulin resistance is a
breakdown in inside cell (intercellular) signaling. Insulin is a
biochemical key messenger. It signals proteins called GLUT-4 transporters
(residing within the cell) to rise up to the cell's membrane (cell
wall), where they can grab onto glucose and take it inside the cell.
In patients with insulin resistance, the cells don't get the message.
They simply can't hear insulin key opening or "knocking"
on the door. This results in elevated blood sugar and insulin. There
could be other additional factors due to lipotoxicity as described
above. Recent studies show high incidence of type 2 diabetes due
to drinking water contaminated with inorganic arsenic; the etiology
of environmental causes of type 2 diabetes is beginning to unravel.6
The liver (as well as intestines and kidneys) which stores the glucose
as glycogen, releases it into the blood during fasting (postprandial)
as glucose in spite of elevated blood sugar and high or low blood
insulin levels. Whatever the causative factor, elevated blood sugar
should be investigated and if found as the problem, therapeutic
agents to reverse or prevent such metabolic change in liver cells
need to be developed. For this we need other therapeutic agents
besides those currently on the market that prevent glucose phosphatase
action and so prevent the conversion of glycogen to glucose and
its subsequent release into the blood. We also need insulin with
different molecular make up (change in the two amino acid chains
and its disulfide bond) that alters this metabolic change, breaks
insulin resistance, and stops the leaking of the glucose form the
liver cells at the same time. Such therapeutic agent (s) when effectively
developed as an oral treatment would be received as "God's
Gift" to diabetics.
· Gestational diabetes is high
blood glucose that develops at any time during pregnancy in about
four percent of all US pregnancies due to insulin resistance caused
by placenta and placental hormones. This condition reverses after
birth of the baby.
· Miscellaneous group: diabetes stemming from genetic defect-related
metabolic syndromes, surgery, drugs, malnutrition, infections,
and other illnesses.
and Diagnostic Tests
Patients develop symptoms over a short (in type 1) or long period
of time (in type 2). These symptoms include increased thirst, urination,
weight loss, increased appetite, fatigue, blurred vision, dry skin,
numbness and tingling in limbs, slow-healing wounds and more infections
than usual, disturbed sleeping, impotence in men, etc.
A urine test alone cannot diagnose diabetes, although it can show
levels of sugar and ketone bodies. The following blood glucose tests
are used to diagnose diabetes:
· Fasting blood glucose level
-- Diabetes is diagnosed if higher than 126 mg/dL on two occasions.
Levels between 100 and 126 mg/dl are considered pre-diabetic and
considered as risk factors for type 2 diabetes.
· Random (non-fasting) blood glucose level -- Diabetes
is suspected if higher than 200 mg/dL and accompanied by the some
of the above symptoms.
· Oral glucose tolerance test -- Diabetes is diagnosed
if glucose level is higher than 200 mg/dL after two hours (This
test is used more for type 2 diabetes.)
· Blood test: The HbA1c is a measure of average blood glucose
during the previous two to three months. It is a very helpful
way to determine how well treatment is working. Ask your doctor
to check it every three months.
· The Ketones test is done using a urine sample. Ketones
are produced by the breakdown of fat and muscle, and they are
harmful at high levels, producing a condition called ketoacidosis.
The public perceives diabetes as a simple raise in blood sugar that
can be cured, curtailed, or controlled by popping a pill or getting
a shot. They fail to realize the lifelong list of debilitating diseases
and deadly complications that afflict diabetics unless proper levels
of blood sugar are maintained with antidiabetic therapy and proper
diet, weight control, and exercise. The following is partial list
of such health problems:
1. Heart disease up to four times higher
among diabetics, resulting in atherosclerosis and coronary artery
2. Stroke is two to four times higher in diabetics.
3. Diabetic retinopathy, leading to blindness in uncontrolled
4. Peripheral neuropathy, leading to pain or a loss of feeling
in the limbs, foot ulcers and foot infections, and the possibility
of an amputation
5. Nerves that control a single muscle or group of muscles can
lose their function resulting in eye movement problems with double
vision or drooping of the cheek on one side of the face due to
6. Kidney diseases needing dialysis (nephropathy)
7. Hypertension and increased cholesterol (hyperlipidemia),which
can lead to ASVD, myocardial infarction (MI), stroke, blood clots.
8. Gangrene and chronic infection of limbs with non-healing wounds
needing surgical intervention such as amputations
9. Congenital birth defects and high incidence of still births
among diabetic pregnant women
10. Infection of the body, especially respiratory system (influenza
and pneumonia), due to less resistance to infection.
11. Stomach and bowel affliction can result in nausea, constipation,
or diarrhea; a stomach that is slow to empty it contents in diabetics
is called gastroparesis.
12. Impotence is common due to nerve and blood vessel damage from
13. The most important painful complication of diabetes is increased
incidence of cancers of every kind.
14. Premature Death: According to National Institute of Diabetes
and Digestive and Kidney Diseases, diabetes is a seventh-leading
cause of death, causing 193,140 deaths in 1996. Think about this:
in middle-aged non-diabetics, the early death rate is 50% less
compared than that in similarly aged diabetics.
15. Every year, 10,000-30,000 people with diabetes die of complications
from flu or pneumonia. They are roughly three times more likely
to die of these complications than people without diabetes.
Complications of diabetes are attributed
to excessive sugar in the blood and tissues binding to proteins
called excessive glycosylation, especially in blood vessels, peripheral
nerves, brain, eyes, etc., as well as excessive build-up of sorbitol
inside cells. Glycosylation is a biological and biochemical chronic
process through which sugar molecule binds irreversibly to a protein.
Because diabetics have higher levels of glucose in their blood for
longer durations, compared to non-diabetics, this results in a higher
degree of glycosylation – a abnormal protein complex structure
laid all over body tissues. Excessive glycosylation leads to multiple
cellular dysfunctions including inactivation of enzymes, inhibition
of regulatory molecule binding, decreased susceptibility to proteolysis,
abnormalities of nucleic acid function, altered macromolecular recognitions,
Sorbitol is produced as a byproduct of glucose metabolism inside
every cell in the body through the action of aldose reductase enzyme.
In non-diabetics, sorbitol is converted to fructose and is excreted
from the cells. Inside the cells of diabetics, however, when glucose
levels become elevated, sorbitol is produced faster than it can
be broken down and expelled. Since sorbitol cannot cross the cell
membrane or break down to fructose to be expelled, it builds up
to a toxic level inside the cells, creating an imbalance that results
in loss of electrolytes and other minerals. This accumulated sorbitol
draws water into the cell by the simple process of osmosis, leading
to the collapse of its architecture and loss of its function, especially
in peripheral nerves (neuropathy), blood vessels (ASVD, coronary
artery disease), the cells of the retinal blood vessels (diabetic
retinopathy), the lens of the eye (cataract), the pancreas (pancreatitis),
the kidneys (nephropathy with kidney failure), and the heart (myocardial
infarction and other organ diseases). The changes in the genetic
material in the cells caused by the rapid division of cells stimulated
by high levels of blood and tissue insulin also may ultimately lead
to cancers and their spread.
For type 1 diabetes, the only treatment is insulin injections. Pregnancy
diabetes is treated with insulin and a change in diet. For type
2 diabetes, the treatment is threefold:
1. Exercise, reduce body weight, eat
less calories, control refined sugar intake, and take proven over-the-counter
supplements that may cure the condition. Consider drinking arsenic-free
2. Take oral medications that increase insulin production (glimepiride,
glipizide, glyburide, repaglinide, nateglinide, and sitaglyptin)
or reduce resistance to insulin at cellular level and increase
sensitivity (metformin, rosiglitazone, and pioglitazone) or medication
that reduces sugar absorption from the intestines (acarbose and
miglitol). Inhalable insulin does not replace natural insulin
production. The alterations in the lifestyle – a balanced
diet and good exercise – along with anti-diabetic therapy
are the most effective way of controlling this chronic disease.
Consider taking one of the alternative over-the-counter supplements
3. Persons with type 2 diabetes may not require insulin to survive,
although about 30% will benefit from insulin therapy to control
the blood glucose. It is estimated that up to 20% of individuals
in whom type 2 diabetes was the initial diagnosis may in reality
have both type 1 and type 2 or type 2, slowly leading to type
1, requiring full insulin replacement. This is said to be due
to destruction of insulin-producing cells by high lipids (lipocentric
theory).3-5 A combination of above treatment modalities
with addition of insulin injections may be called for. These patients
along with the type 1 diabetics are targeted for use of inhaled
insulin, oral and nasal insulin sprays, and oral-rectal insulin.
How Insulin Transports Blood Sugar into
The role of insulin is a very complex
biological and biochemical one at cellular levels. The liver plays
a primary role in removing and storing glucose from the blood after
a meal and releasing it for energy needs when the blood sugar level
drops between meals. Each cell in the body has a cell membrane around
it much like the thin covering on a grape. These cell membranes
are the gatekeepers for various substances in and out of cells including
sugar. These membranes have various kinds of receptors (locked doors)
that open or shut for the entry and exit of these biological and
nutritional substances. These doors are unlocked by specific biological
keys (such as insulin).
Cells have insulin receptors (IR) and insulin-like growth factor
receptors (IGFR-l, II) – locked doors on the cell membrane
that can be opened (i.e., activated) by the insulin key. Without
these, sugar, proteins, and fats cannot enter the cell through the
cell membrane. Once insulin activates the activity on the surface
and inside the cell, a small protein (polypeptide-GLUT-4) molecule
moves towards the cell membrane, binds to these opened receptor
doors, locks onto the cell membranes, binds to the glucose outside
the cell membrane, and literally drags the sugar-bound protein through
these biologically insulin-activated unlocked doors into the cell
to be used for energy production. Insulin activates various biological
activities, resulting in a host of biochemical reactions and allowing
large amounts of sugars, amino acids, and other nutrients, including
electrolytes (needed for cell energy, protein production, and cell
division to maintain the healthy body) into the cell. Insulin also
helps store sugar in the liver (mainly) and in other cells as glycogen
to be released between meals when blood sugar falls and/or to be
used as needed by the cells. Sugar's entry into the liver
(some in other cells) from the blood reduces the circulating elevated
blood sugar after meal. Elevated blood sugar after meal also triggers
the release of insulin (from the pancreas to portal circulation),
which enters the liver and clears the elevated blood sugar. Insulin
increases the rate of glucose transport by ten times or more. That
tells us what an important role insulin plays in lowering the blood
Cancer and Insulin
Cancer and precancerous cells develop anaerobic (less oxygen) metabolism,
as described by Nobel laureate Otto Warburg almost 75 years ago.
Due to this metabolic defect, cancer cells only produce 15% of the
energy needed for cellular activity and multiplication. To overcome
the energy deficit, these cells need more sugar. If they have normal
insulin receptors like normal healthy cells, they will be starved
to death and will not grow or spread to distant organs. As normal
cells change to anaerobic factory (cancer) needing lots of sugar,
they develop almost three to ten times more insulin and insulin-like
growth factor receptors, allowing three to ten times more sugar
into cells to meet this metabolic demand. More insulin receptors
mean more insulin binds on the cancer cell surface and more glucose
and amino acid enters the cell to meet the metabolic need to multiply
Cancer cells also need insulin and insulin-like growth factors for
protein synthesis, which is needed for growth, multiplication, and
spread. Insulin with growth hormone and insulin-like growth factors
enhance the uptake of amino acids into cancer cells, increases the
translation of messenger RNA (thus forming new proteins), and increases
the rate of transcription of DNA in the cell nuclei (thus forming
increased quantities of RNA). This is the result of the evolution
of normal cells to cancer cells that multiply with uncontrolled
ease. In summary, insulin greatly enhances the rate of protein formation
– providing sugar for energy needs – and enhances the
cell division in cancer cells. That is why cancer cells grow uncontrolled
with the help of numerous insulin and insulin-like growth factor
receptors activated by insulin. In true sense, high levels of insulin
at the cell level are carcinogenic due to the abnormal biological
changes they bring in the cell lifecycle.
You can see that the abnormal precancerous cells and cancer cells
flourish with an additional supply of insulin directly deposited
on insulin receptors with the use of inhalation insulin, nasal and
oral insulin sprays, and oral or rectal insulin. It has been shown
that even the nanomolar concentration of IGF-I and IGF-II are potent
mitogens, meaning that these stimulate cell division and proliferation.
Can you think of what could happen to the cells of a vulnerable
population, for instance, aged smokers exposed to irritations and
toxic chemicals (including tobacco), which already are working to
transform normal cells into cancer cells? The threat of tumors (cancers),
infections, and other diseases looms with the prolonged, stand-alone
use of inhalation insulin, insulin oral or nasal sprays, oral swallowed
insulin and rectal suppository treatments.
Diabetes and Cancers
As you know by now, insulin is a double-edged sword: we know that
it controls sugar in the blood to prevent diabetes; at the same
time, insulin also contributes to many diseases in type 2 diabetics
as described above. Here is the problem: as cells become resistant
to insulin, type 2 diabetes results. This, in turn, results in more
sugar circulating in the blood because there's no sugar uptake
within insulin-resistant cells. In response to elevated blood sugar,
insulin-producing cells produce more insulin. This insulin starts
to circulate in the blood. As described above, abnormal cells and
cancer cells have more insulin and IGF receptors. Studies have shown
that cancer cells need energy in the form of sugar due to anaerobic
metabolism. The circulating high insulin provides energy through
glucose metabolism to these cancer and precancerous cells, which
helps them to multiply rapidly by enhancing the protein syntheses
and providing energy through sugar. That is why diabetics experience
higher cancer rates than non-diabetics. Interestingly, insulin-producing
cells reduce or stop producing insulin over time in type 2 diabetics,
which again increases blood sugar that needs exogenous insulin to
control blood sugar.
Insulin and Cancers
Before you start using insulin through inhalation, oral and nasal
spray, oral, or rectal suppository delivery systems, I want to offer
the following. If you go online to and www.
Pubmed.gov and search for "insulin and cancer," you
will find 17,089 citing; if you search "insulin causes cancer,"
you will find 9079 citing. This indicates the intense research on
the relationship of insulin to cancer. It is well-established that
type 2 diabetics do develop more cancers than non-diabetics, and
insulin plays a major role in multiplication of cancers cells and
their spread. All cancer and precancerous cells have up to ten times
more IR and IGFR-I than normal cells to which insulin does bind.
Even solitary non-cancerous fibrous tumors besides prostate and
other types of caners have IGF receptors.8-12 Several
epidemiological studies have shown that insulin resistance states
are characterized by high levels of insulin in the blood (hyperinsulinemia)
and are associated with an increased risk for a number of tumors,
including carcinomas of the breast, prostate, colon, kidney, and
other organs. Recent data have elucidated some molecular mechanisms
by which insulin is involved in cancer. It is well-known that the
insulin receptors are over-expressed in all human cancers.13 According
to various studies, there is hardly a precancerous or cancer cell
in which the insulin receptors are not over-expressed. Why do the
cancers need that many insulin receptors? Without the ability to
bind to the receptors on the cancer cell wall, insulin has no effect
on the transport of glucose for energy production and protein synthesis
– i.e., cancer will not grow and spread.
Inhaled Insulin and Nasal and Oral Insulin Spray Therapies for Diabetes
Unprecedented demand for insulin-dependent diabetes mellitus therapy
coupled with the unmet need for non-invasive alternatives to subcutaneous
insulin injection make diabetes one of the most attractive profitable
therapy areas for the pharmaceutical industry to develop inhalation,
oral and nasal spray insulin, and oral or rectal pill hormone delivery
of insulin-based products. (Exubera was the first such FDA-approved
product in the market to deliver the insulin by inhalation insulin.
Exubera has now been withdrawn from the market for safety reasons.)
Important routes targeted for developing alternative (to subcutaneous
injection) insulin delivery systems are the nose, mouth, lungs,
skin, and digestive system.
The following are some of the research centers and pharmaceutical
companies that are experimenting to provide inhaled insulin, oral
and nasal sprays, and oral and rectal insulin pills with diverse
1. Pfizer and Aventis collaborated
with Nektar Therapeutics (formerly Inhale Therapeutics), a company
that specializes in finding delivery solutions for oral, injectable,
and pulmonary drug administration. They marketed the FDA-approved
"Exubera inhaler" to deliver insulin content that
coats the anatomical structures before it reaches the deeper depths
of alveoli; only ten percent of the insulin is absorbed, and the
rest is lost.
2. Eli Lilly, along with Alkermes, is developing "AIR Insulin,"
which is expected to be submitted for approval in 2009; this treatment
has been under development since 2001.
3. Mannkind and Technosphere Insulin System are developing a palm-sized
inhaler device with a special formulation that allows pH sensitive
carrier particles to be carried deep into the lungs and release
insulin. This is a powder that will be deposited on the air passages
before it reaches the lung alveoli.
4. Novo Nordisk has partnered with Aradigm to produce the only
inhaled insulin in clinical trials that uses a liquid formulation.
Known as AERx Insulin Diabetes Management System, again it sticks
to various anatomical structures before it reaches lung alveoli
and has the same adverse effect as inhaled insulin powder.
5. Andaris, in Nottingham, England, acquired in 2003 by Cambridge-based
Quadrant developed a 5 micron hollow microcapsule of insulin using
a low temperature, spray technique that preserves the insulin
structure. This insulin microcapsule can be inhaled directly into
the lungs for absorption. Quadrant is now working with Innovata,
MicroDose Technologies, and Bristol-Meyers Squibb to develop this
Q Dose inhaled insulin product.
6. Biodel, Inc., located in Danbury, Connecticut, is a specialty
pharmaceutical company that develops novel formulations of FDA-approved
Biodel's proprietary VIAdel™ technology, which allow for
a more effective delivery of endocrine therapeutics as well as
one with increased efficacy and safety. They are developing patented
technology applicable to a wide range of peptides, proteins and
other macromolecules, including insulin. Biodel's lead drug candidates
VIAject™, a very rapid-acting injectable insulin, and VIAtab™
are said to utilize a rapidly acting oral sub-lingual insulin,
and no one knows what else is in the works by this ingenious founder
of the company.
7. Generex Biotech Pharma and many other drug companies are working
on different ways to deliver insulin. Generex, a biotechnology
company, has developed rapid mist oral delivery insulin (Oral-Lyn)
that is absorbed by the buccal mucosa and currently approved for
use in Ecuador. This company has an agreement to develop the treatment
for the US with insulin giant Eli Lilly. Long-term use can result
in oral cancers, especially in smokers and tobacco chewers.
8. Companies like Aradigm, Novo Nordisk, Wockhardt, Emisphere,
US-based Nobex in collaboration with India-based Biocon, Oramed
Pharmaceutical of Israel, Sree Chitra Tirunal Institute of India,
and countless others are all working to develop oral and other
modes or routes for insulin delivery systems.
9. Many companies are developing or have developed devices for
transdermal delivery of insulin without pain, using passive delivery
systems with a patch, cream, spray, continuous infusion, micro
needle patch, rapid injectors, etc. The skin is a formidable barrier.
Active transdermal delivery involves a chemical or mechanical
disruption of the skin barrier by an applied force, such as ultrasound
or an electrical current, as well as through chemicals. These
developments include Dermisonics, which has integrated microelectronics
and ultrasonic science into a skin pad called the U-Strip; the
Medi-Cap, a transdermal patch that holds the insulin and is applied
to the skin; the Ultrasonic Applicator and Dose Controller generates
ultrasonic transmissions to dilate the pores and allow large molecule
drugs to enter the bloodstream; the Medingo insulin-dispensing
patch, called the Solo™, adheres directly to the skin with
no tubing or other connections (the Solo™ system includes
the patch and a separate remote control unit); Vyteris transdermal
drug delivery uses an Iontophoretic delivery technology that delivers
drugs comfortably through the skin using low-level electrical
energy; and continuous subcutaneous insulin delivery pumps are
also available and in use by many type 1 diabetics. Many such
devices are in the horizon. Most of these devices are cumbersome
to wear and difficult to operate and, hence, are not popular.
High Dose of Inhalation Insulin Used to Achieve Blood Levels in
the Lungs to Lower Blood Sugar
Inhalation and nasal and oral spray insulin is effective only when
the calculated dose is at least three to five times the amount given
by injection under the skin. Only little more than ten percent of
inhaled or aerolised or swallowed insulin is bio-available and able
to reduce blood sugar. These therapy modes do not yield 100% dose-dependent
effects in lowering the sugar. Further, insulin has to be tagged
to other substances to reach alveolar, mouth and nasal surfaces,
be absorbed, and effectively reduce blood sugar in insulin-dependent
Let's look at what happens to insulin delivered through inhalation
and nasal and oral spray delivery systems:14
1. Some insulin remains in the original
container after inhalation or spray.
2. Some insulin adheres to the inner surfaces of the inhaler and
3. Larger particles (containing a lot of insulin) are deposited
in the mouth, throat, Nose, and tracheo-bronchial tree (breathing
4. Some insulin particles are exhaled through the nasopharyngeal
outlet without being deposited in the alveoli.
5. When insulin passes through the nasal passage in exhaled air,
some particles enter the nasal air passages (sinuses) and nasal
lining as well as landing on the olfactory mucosa which has direct
connection to the brain.15
6. Some insulin deposited in the alveoli is taken up by macrophages
and other lining cells.
7. Finally, the aerolised insulin-containing particles deposited
on the deepest part of the lungs (alveolar mucosa), oral, and
nasal mucosa are absorbed by the systemic circulation. They enter
the heart, then circulate all over the body, binding to insulin
receptor, and performing the physiologic function of reducing
blood sugar and enhancing the protein synthesis.
8. It is interesting to note only 25% of this insulin reaches
the liver (due to 25% of cardiac output reaching liver), whereas
100% of the endogenous natural insulin produced in response to
high blood sugar after meal passes through the liver where an
estimated 60% of it is used by liver cells and the rest enters
the systemic circulation from the liver. Even oral insulin does
not reach liver like natural pancreatic insulin. Only 30-40% of
orally absorbed insulin reaches the liver.
It is obvious that only a small part
of inhaled insulin and nasal and oral insulin spray gets into circulating
blood to reduce blood sugar. Because of the reasons detailed above,
to achieve the proper levels in blood, inhalation or spray methods
are formulated with far more insulin so that they can achieve the
concentration needed to lower blood sugar. This makes make these
products very expensive to produce. The onset of action with inhaled
insulin and nasal and oral insulin spray is more rapid than that
found with the use of subcutaneously administered rapid-acting analogue
due to the difference between the large absorbing surface of the
lung alveoli, oral and nasal mucosa affected by the former as compared
to the areas affected by subcutaneous injection.15
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