The Laboratory Diagnosis and management of Diabetic Coma
Diabetes is any disorder of the metabolism which causes excessive thirst and the
production of large volumes of urine. A coma is a state of unrousable unconsciousness.
(Martin (2002)) There are two types of diabetes:
Diabetes Insipidus (DI) is a rare metabolic disorder, the symptoms of which are the
production of large quantities of dilute urine and an increased thirst. It is caused by a
deficiency of the pituitary hormone Anti-diuretic hormone (ADH / vasopressin) which
regulates water reabsorption in the kidneys. (Martin (2002))
Diabetes Mellitus (DM) has symptoms of polyuria, wasting and glycosuria (mellitus
means sweet urine) as well as the following tests to give a laboratory diagnosis of DM:
Venous plasma glucose >11.1 mmol / L or
Fasting venous plasma glucose > 7.0 mmol / L or
Plasma venous glucose concentration > 11.1 mmol / L two hours after taking 75 g glucose
in an oral glucose tolerance test (OGTT).
There are two types of DM; insulin dependent DM (IDDM or type 1) and non-insulin
dependent DM (NIDDM or type 2)
Type 1 is caused by the destruction of pancreatic b cell destruction, which can be predicted
by the detection of the presence of antibodies (Abs) to islet cells, (Pitteloud, Philippe
(2000)) insulin and glutamic acid dehydrogenase (GAD) (a neurotransmitter) and a
decrease in b cell insulin secretion. This destruction causes a decrease in insulin
production, the hormone which stimulates glucose to be stored in the muscle and liver as
glycogen.
Type 1 causes an abrupt onset of severe symptoms, including a tendency to ketosis and a
dependence on exogenous insulin.
Type 2 is caused by a diet high in saturated fats, a lack of exercise and obesity. This is
because the constantly high glucose levels cause insulin to be produced at constantly high
levels, and so the body becomes desensitized to its effect as cells in target tissues posses
fewer insulin receptors. Characteristics of NIDDM are that insulin is present, symptoms
are moderate (tiredness and thirst), there is no tendency to ketosis and patients are not
dependent on exogenous insulin. High blood glucose is controlled by diet, possibly with
diabetic drugs.
Complications of DM are:
Cataract, as excessive blood glucose binds to lens proteins.
Retinopathy (micro-angiopathy) caused by hemorrhage, etc..
Neuropathy, both peripheral and CNS, affecting the furthest points of longest nerves first,
e.g. diabetic foot.
Peripheral vascular disease, causing impotence and ulcerated foot.
Diabetic nephropathy, with albuminaemia, renal failure and cardiovascular disease, and
psychological aspects.
In DM ketosis is caused because of the use of fat as an alternate energy source to glucose,
