All other specific forms of diabetes, accounting for up to 5% of all diagnosed
cases of diabetes, are termed Type 3:
Type 3A: genetic defect in beta cells.
Type 3B: genetically related insulin resistance.
Type 3C: diseases of the pancreas.
Type 3D: caused by hormonal defects.
Type 3E: caused by chemicals or drugs.
Type 4 "Gestational Diabetes Mellitus"
Type 4 or Gestational diabetes mellitus appears in about 2-5% of all
pregnancies. It is temporary and fully treatable, but if untreated it
may cause problems with the pregnancy. It requires careful medical
supervision during the pregnancy. In addition, about 20-50% of these
women go on to develop Type 2 diabetes.
Both Type 1 and Type 2 diabetes are at least partly inherited.
► Type 1
Appears to be triggered by infection, stress, or environmental
factors (e.g. exposure to a causative agent). There is a genetic element
in the susceptibility of individuals to some of these triggers which has
been traced to particular HLA genotypes (i.e. genetic 'self' identifiers
used by the immune system). However, even in those who have inherited
the susceptibility, Type 1 diabetes mellitus seems to require an
Type 1 diabetes is rare in Arab countries; in Libya, for example, type 1
diabetes accounted for only 2.2% of 10.772 people diabetes.
► Type 2 D.M.:
There is an even stronger inheritance pattern for Type 2 diabetes; those
Type 2 ancestors or relatives have very much higher chances of
developing Type 2. It is also often connected to obesity, which is found
in approximately 85% of (North American) patients diagnosed with that
form of the disease, so inheriting a tendency toward obesity seems also
to contribute. Age is also thought to be a contributing factor, as most
Type 2 patients in the past were older. The exact reasons for these
connections are unknown.
Diagnosis of Diabetes Mellitus:
► The diagnosis of type 1 diabetes:
Is usually prompted by recent symptoms of excessive urination (polyuria) and
excessive thirst (polydipsia), often accompanied by weight loss.
These symptoms typically worsen over days to weeks; about 25% of people with new
type 1 diabetes have developed diabetic
ketoacidosis by the time the diabetes is recognized.
► The diagnosis of other types of diabetes:
It is made in many other ways. The most common are
(1) health screening,
(2) detection of hyperglycemia when a doctor is investigating a complication of
longstanding, unrecognized diabetes, and less commonly
(3) new signs and symptoms attributable to the diabetes.
Diabetes screening is recommended for many types of people at various stages
of life or with several different risk factors. The screening test varies
according to circumstances and local policy and may be a random glucose, a
fasting glucose and insulin, a glucose 2 hours after
75 g of glucose, or a formal glucose tolerance test. Many health care
recommendations for adults recommend universal screening at age 40 or 50 years,
and sometimes occasionally thereafter.
Many medical conditions are associated with a higher risk of various types of
diabetes and warrant screening. A partial list includes: hypertension,
dyslipidemia, coronary artery disease, past gestational diabetes, polycystic
ovary syndrome, chronic pancreatitis, hepatic steatosis (fatty liver), cystic
fibrosis, several mitochondrial neuropathies and myopathies, myotonic dystrophy,
Friedreich's ataxia, some of the inherited forms of neonatal hyperinsulinism and
many others. Risk of diabetes is higher with chronic use of several medications,
including high dose glucocorticoids, some cancer chemotherapy agents (especially
L-asparaginase), and some of the antipsychotics and mood stabilizers (especially
Diabetes is often detected when a person suffers a problem frequently caused by
diabetes, such as a heart attack, stroke, neuropathy, poor wound healing or a
foot ulcer, certain eye problems, certain fungal infections, or delivering a
baby with macrosomia or hypoglycemia.
Type 2 diabetes can sometimes be recognized because of excess urination and
thirst, fatigue, leg or foot pain, or (occasionally) ketoacidosis or lethargy
due to extreme hyperglycemia.
Criteria for diagnosis Diabetes Mellitus:
Is characterized by recurrent or persistent hyperglycemia, and is diagnosed by
demonstrating any one of two fasting plasma glucose levels above 7 mmol/l (125
mg/dl in US) on different days; plasma glucose above 11 mmol/l (200 mg/dl in US)
two hours after a 75 g glucose load; or symptoms of diabetes and a random
glucose above 11 mmol/l (200 mg/dl). elevated glucose bound to hemoglobin,
HbA1c, of 6.0% or higher (2003 revised US standard); this is a screening and
treatment-tracking test reflecting average blood glucose levels over the
preceding 90 days (approximately).
Signs and symptoms:
||Type 2 diabetes
- Particularly in children, onset may be quite fast (weeks or
- Early symptoms of Type 1 diabetes are often polyuria (frequent
urination) and polydipsia (increased thirst, and consequent
increased fluid intake). There may also be weight loss (despite
normal or increased eating), increased appetite, and unreducable
- almost always has a slow onset (often years)
- Same symptoms may also manifest in Type 2 diabetes, though this
seldom happens for some years, and sometimes not at all. Clinically,
it is most common in Type 2 patients who appear at the doctor with
frank poorly controlled diabetes.
- Thirst develops because of osmotic effects — sufficiently high
glucose (above the 'renal threshold') in the blood is excreted by
the kidneys but this requires water to carry it and causes increased
fluid loss, which must be replaced. The lost blood volume will be
replaced from water held inside body cells, causing dehydration
- Altered vision. Prolonged high blood glucose causes changes in
the shape of the lens in the eye, leading to blurred vision and,
perhaps, a visit to an optometrist. All unexplained quick changes in
eyesight should force a fasting blood glucose test.
- Kussmaul breathing (a rapid, deep breathing), and any altered
state of consciousness or arousal (hostility and mania are both
possible, as is confusion and lethargy).
- The most dangerous form of altered consciousness is the
so-called "diabetic coma" which produces unconsciousness.
- Early symptoms of impending diabetic coma include polyuria,
nausea, vomiting and abdominal pain, with lethargy and somnolence a
later development, progressing to unconsciousness and death if
Hyperosmotic diabetic coma:
Hyperosmotic diabetic coma is another acute problem
associated with improper management of diabetes mellitus. It has some symptoms
in common with DKA, but a different cause, and requires different treatment. In
anyone with very high blood glucose levels (usually considered to be above 300
mg/dl) water will be osmotically driven out of cells into the blood. The kidneys
will also be "dumping" glucose into the urine, resulting in concomitant loss of
water, causing an increase in blood osmolality. The osmotic effect of high
glucose levels combined with the loss of water will eventually result in such a
high serum osmolality that the body's cells may become directly affected as
water is drawn out from them. Electrolyte imbalances are also common. This
combination of changes, especially if prolonged, will result in symptoms similar
to ketoacidosis, including loss of consciousness. As with DKA, urgent medical
treatment is necessary. This is the diabetic coma to which Type 2 diabetics are
prone; it is less common in Type 1 diabetics.
Hypoglycemia in diabetic patients almost always arises as a result of poor
management of the disease either from too much or poorly timed insulin or oral
hypoglycemics or too much exercise, not enough food, or poor timing of either.
Long term complications:
Among the major risks of the disorder are chronic problems affecting multiple
organ systems which will eventually arise in patients with poor glycemic
control. Many of these arise from damage to the blood vessels. These illnesses
can be divided into those arising from large blood vessel diseases,
macroangiopathy, and those arising from small blood vessel disease, retinopathy
which can lead to blindness; peripheral neuropathy which, particularly when
combined with damaged blood vessels, can lead to foot ulcers, and possibly
progressing to necrosis, infection and gangrene, sometimes requiring limb
amputation, see below nephropathy which can lead to renal failure Large vessel
disease complications: ischemic heart disease caused by both large and small
vessel disease stroke peripheral vascular disease which contributes to foot
ulcers and the risk of amputation Diabetes mellitus is the most common cause of
adult kidney failure worldwide. It also the most common cause of amputation in
the US, usually toes and feet, often as a result of gangrene, and almost always
as a result of peripheral vascular disease. Retinal damage (from microangiopathy)
makes it the most common cause of blindness among non-elderly adults in the US.