Diabetes mellitus is a medical disorder characterized by varying or persistent
hyperglycemia (elevated blood sugar levels), especially after eating.
Hypoglycemia (low blood sugar) is rare except as a side effect of treatment
(usually misapplication of medication in particular circumstances).
Historically, physicians have focused on two factors that are characteristic of
1- Decreased production of insulin (the first recognized basis),
2- Decreased sensitivity of body tissues to insulin (the more common),
3- A combination of both.
The distinction between these two circumstances remains important.
Types of Diabetes:
Hyperglycemia itself can lead to :
While there are different types of diabetes mellitus, most are asymptomatic for
a (variable) time after onset, but all share similar symptomatology and
complications at advanced stages. This disease involves multiple casual factors
and clinical aspects, all of which should be well understood for better
Patient understanding and participation is highly desired as blood glucose
levels change continuously in response to exercise, diet, physical and
psychological stress, infection, accident (i.e., trauma), hormonal changes, and
even (perhaps) phase of the moon; the diabetic patient is the only person
present or experiencing all of these.
- Dehydration and ketoacidosis
- Longer-term complications include cardiovascular disease (doubled risk - equal rates to those with heart attacks)
from advanced atherosclerotic disease.
- Renal failure (worldwide, diabetes mellitus is the most common cause of chronic renal failure requiring renal dialysis)
- Retinal damage with eventual blindness
- Nerve damage and eventual gangrene with probable loss of toes, feet, and even legs.
Conversely, successfully keeping blood sugar normal at all times, despite
the difficulty of doing so (especially 0.5 to about 4 hours after eating) has
been compellingly shown to reduce/prevent each of these problems.
Other factors that can, and should, be controlled to reduce problems associated with diabetes include:
- Not smoking
- Optimizing lipoprotein cholesterol patterns, reducing body fat
- Exercising regularly, preferably with increasing intensity (Pima Indians often cease to be diabetic after becoming long distance runners)
WHO criteria - sampling & screening procedures:
In 2004, according to the World Health Organization, more than 150 million
people worldwide suffer from diabetes. Its incidence is increasing rapidly, and
it is estimated that by the year 2025 this number will double.
occurs throughout the world, but is more common (especially Type 2) in the more
Causes and types of diabetes mellitus:
The role of insulin Since insulin is the principal hormone that makes it
possible for many cells (primarily muscle and fat cells) to use glucose from the
blood, deficiency of insulin or its action plays a central role in all forms of
Most of the carbohydrates in food are rapidly digested to glucose, the principal
sugar in blood. Insulin is produced by beta cells in the
pancreas in response to
rising levels of glucose in the blood, as occurs after a meal. Insulin makes it
possible for most body tissues to remove glucose from the blood for use as fuel,
for conversion to other needed molecules, or for storage. Insulin is also the
principal control signal for conversion of glucose, the basic sugar unit, to
glycogen for storage in liver and muscle cells. Lowered insulin levels result in
the reverse conversion of glycogen to glucose when glucose levels fall -- though
only in the liver not muscle tissue. Higher insulin level increase many anabolic
("building up") processes such as cell growth, cellular protein synthesis, and
fat storage. Insulin is the principal signal in converting many of the
bidirectional processes of metabolism from a catabolic to an anabolic direction.
if the amount of insulin produced is insufficient, if cells respond poorly to
the effects of insulin (resistance or insulin insensitivity), or if the insulin
itself is defective, glucose is not handled properly by body cells (about 2/3
require it) nor stored appropriately in the liver and muscles. The net effect is
persistent high levels of blood glucose, poor protein synthesis, and other
Type I diabetes mellitus:
Formerly, Type I diabetes was called "childhood" or "juvenile" diabetes or
"insulin dependent" diabetes.
Each term is a misnomer, most especially since the obesity epidemic in
recent years has led to increased incidence of Type II diabetes in children and
adolescents and insulin is used in some Type II cases.
Artificial Type I Diabetes:
- Type II diabetes is most commonly diagnosed in children and adolescents, but can occur in adults as well. It is an autoimmune disorder, in which the body's own
immune system attacks the beta cells in the Islets of Langerhans of the pancreas, destroying them or damaging them sufficiently to reduce insulin
production. The autoimmune attack may be triggered by reaction to an infection, for example by one of the viruses of the Coxsackie virus family.
- A subtype of Type I (identifiable by the presence of antibodies against beta cells) develops slowly and so is often confused with Type
- In addition, a small proportion of Type I cases has the hereditary maturity onset diabetes of the young (MODY).
- Some poisons (e.g., a type of rat poison) work by selectively destroying certain types of cells, including pancreatic beta cells,
thus producing 'artificial' Type I diabetes.
- Other pancreatic problems including trauma or tumor (either malignant or benign) can also lead to loss of insulin production and Type
Treatment of Type I D.M.:
- Currently, Type 1 is treated with insulin injections, lifestyle adjustments, and careful monitoring of blood glucose levels using blood test kits. The treatment
must be continued indefinitely.
- Experimental replacement of beta cells (by transplant) is being investigated in several research programs and may become clinically available in future. About 5-10% of
all North American cases of diabetes are Type 1 diabetics. The fraction of Type 1 diabetics in other parts of the world differs; this is likely due to both
differences in the rate of Type 1 and differences in the rate of other Types,most prominently Type 2. Most of this difference is not currently understood.
II diabetes mellitus:
Type 2 diabetes was formerly known by a variety of partially misleading
names, including "adult-onset diabetes", "obesity-related diabetes",
"insulin-resistant diabetes", or "non-insulin-dependent diabetes" (NIDDM).
Type II diabetes is characterized by "insulin resistance" as body cells do not
respond appropriately when insulin is present. This is a more complex problem
than type 1, but is sometimes easier to treat, since insulin is still produced
in many, especially in the initial years.
Treatment of Type II D.M.:
Type II may go unnoticed for years in a
patient before diagnosis, since the symptoms are typically milder (no
ketoacidosis) and can be sporadic. However, severe complications can result from
unnoticed Type 2 diabetes, including hypertension, renal failure, and coronary
It may be caused by a
number of diseases, such as hemochromatosis and
polycystic ovary syndrome, and
can also be caused by certain types of medications (e.g., long-term steroid
Type 2 Diabetes in the Arab World is the subject of the present essay, which
gives update of the present rate and where possible, a historic perspective. It
takes a look at Obeisty and sedentary life-style, two common risk factors for
The fraction of
Type II diabetics in other parts of the world varies substantially, almost
certainly for environmental reasons.
There is also a very strong inheritable
genetic connection in type 2 diabetes - having relatives, especially close ones,
with type 2 is a considerable risk factor for developing type 2 diabetes. Most
patients with type 2 diabetes mellitus are obese - chronic obesity leads to
increased insulin resistance that can develop into diabetes, most likely because
fat tissue is a (recently identified) source of chemical signals (ie, hormones).
- Type II is initially treated by changes in diet and through weight loss. This can restore insulin sensitivity, even when the weight lost is modest (e.g. 10-15 lbs
or 5 kg).
- The next step, if necessary, is treatment with oral antidiabetic drugs: the sulphonylureas,
metformin, or (if these are insufficient thiazolidinediones).
- When these have failed,
insulin therapy may be necessary.