Long-term complications of Diabetes Mellitus and diabetes symptoms includes:
- Retinopathy with potential loss of vision;
- Nephropathy leading to renal failure;
- Peripheral neuropathy with risk of foot ulcers, amputations, and Charcot joints; and autonomic neuropathy causing gastrointestinal, genitourinary, and cardiovascular symptoms and sexual dysfunction.
- Patients with diabetes have an increased incidence of atherosclerotic cardiovascular, peripheral arterial, and cerebrovascular disease that can increase the effects Diabetes Mellitus.
- Hypertension and abnormalities of lipoprotein metabolism are often found in people with diabetes.
DIAGNOSIS AND DIAGNOSTIC CRITERIA
The requirements for diagnostic confirmation for a person
presenting with severe symptoms and gross hyperglycaemia differ from those for the asymptomatic person with blood glucose values found to be just above the diagnostic cut–off value. Severe hyperglycaemia detected under conditions of acute infective, traumatic, circulatory or other stress may be transitory and should not in itself be regarded as diagnostic of diabetes. The diagnosis of diabetes in an asymptomatic subject should never be made on the basis of a single abnormal blood glucose value.
For the asymptomatic person, at least one additional plasma/blood glucose test result with a value in the diabetic range is essential, either fasting, from a random (casual) sample, or from the oral glucose tolerance test (OGTT). If such samples fail to confirm the diagnosis of diabetes mellitus, it will usually be advisable to maintain surveillance with periodic re–testing until the diagnostic situation becomes clear.
In these circumstances, the clinician should take into consideration such additional factors as ethnicity, family history, age, adiposity, and concomitant disorders, before deciding on a diagnostic or therapeutic course of action. An alternative to blood glucose estimation or the OGTT has long been sought to simplify the diagnosis of diabetes. Glycated haemoglobin reflecting average glycaemia over a period of weeks, was thought to provide such a test.
Although in certain cases it gives equal or almost equal sensitivity and specificity to glucose measurement (McCance et al., 1994), it is not available in many parts of the world and is not well enough standardized for its use to be recommended at this time.
The clinical diagnosis of diabetes is often prompted by symptoms such as increased thirst and urine volume, recurrent infections, unexplained weight loss and, in severe cases, drowsiness. These criteria are as in the 1985 report. For clinical purposes, an OGTT to establish diagnostic status need only be considered if casual blood glucose values lie in the uncertain range (i.e. between), the levels that establish or exclude diabetes) and fasting blood glucose levels are below those which establish the diagnosis of diabetes.
If an OGTT is performed, it is sufficient to measure the blood glucose values while fasting and at 2 hours after a 75g oral glucose load (Annexes 1 and 2).
For children the oral glucose load is related to body weight: 1.75 g per kg. The diagnostic criteria in children are the same as for adults (Alberti et al., 1994).
Change in diagnostic value for fasting Plasma/blood glucose concentrations
The major change recommended in the diagnostic criteria for diabetes mellitus is the lowering of the diagnostic value of the fasting plasma glucose concentration to 7.0 mmol l–1 (126 mgdl–1) and above (World Health Organization. Diabetes Mellitus, 2003), from the former level of 7.8 mmol l–1 (140mg dl–1) and above.
For whole blood the proposed new level is 6.1 mmol l–1 (110 mg dl–1) and above, from the former 6.7mmol l–1 (120 mg dl–1).
The new fasting criterion is chosen to represent a value which is at the upper end of the range that corresponds in diagnostic significance in many persons to that of the 2–h post–load concentration, which is not changed. This equivalence has coma; high levels of glycosuria are usually present. A single blood glucose been established from several population–based studies (6–8) and it also represents an optimal cut–off point to separate the components of bimodal frequency distributions of fasting plasma glucose concentrations seen in several populations. Furthermore, several studies have shown increased risk of micro vascular disease in persons with fasting plasma glucose concentrations of 7.0 mmol l–1 (126mg dl–1) and over (6), and of macro vascular disease in persons with such fasting concentrations, even in those with 2–h values of < 7.8 mmol l-1 (140 mg dl–1) (9). Nevertheless, in less obese subjects, in some ethnic groups and in the elderly lower fasting glucose levels may be seen in persons who have 2–h post–load glucose values that are diagnostic for diabetes.
For epidemiological or population screening purposes, the fasting or 2-h value after 75 g oral glucose may be used alone. For clinical purposes, the diagnosis of diabetes should always be confirmed by repeating the test on another day unless there is unequivocal hyperglycaemia with acute metabolic decompensation or obvious symptoms.
Glucose concentrations should not be determined on serum unless red cells are immediately removed; otherwise glycolysis will result in an unpredictable under-estimation of the true concentrations. It should be stressed that glucose preservatives do not totally prevent glycolysis.
If whole blood is used, the sample should be kept at 0-4 °C or centrifuged immediately, or assayed.
Following the number of complications diabetes mellitus usually present the patient with, which is imposing serious threats on the global health and economy, care should be taken to ensure early proper diagnosis of Diabetes mellitus before it deteriorate to the extent it will be difficult to manage.
Therefore medical laboratory scientists should ensure accuracy, precision and adequacy in carrying out their laboratory investigation for this disease in order to control and manage it to the barest.