Type 3:
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 D.M.:
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 environmental trigger.
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 with
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 phenothiazines).

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 I

Particularly in children, onset may be quite fast (weeks or months). 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 fatigue.


Type II

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 untreated.

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.