Diabetes was once regarded as a single disease entity, but it is now seen as a heterogeneous group of diseases, characterized by a state of chronic hyperglycemia (excess glucose in blood), resulting from a diversity of etiologies, environmental factors and genetic factors, acting together. The underlying cause of diabetes is the defective production or action of insulin (a hormone that controls glucose, fat and amino acid metabolism). Characteristically, diabetes is a long-term disease with variable clinical manifestations and progression. Chronic hyperglycemia, from whatever cause, leads to a number of complications like, ocular (diabetic retinopathy) cardiovascular, renal, neurological, and others such as recurrent infections.
Classification:
The clinical classification adopted by WHO is given below:
(1) Diabetes mellitus (DM)
(i) Insulin-dependent diabetes mellitus (IDDM or Type 1 or diabetes i)
(ii) Non-insulin dependent diabetes mellitus (NIDDM or Type 2 or type ii)
(iii) Malnutrition-related diabetes mellitus (MRDM)
(iv) Other types (secondary to pancreatic, hormonal, genetic drug-induced and other abnormalities)
(2) Impaired glucose tolerances (IGT)
(3) Gestational diabetes mellitus (GMD)
IDDM is one of the most severe from of the diseases. Its onset is abrupt and is usually seen in individuals less than 30 years of age. It should be diagnosed and treated promptly; otherwise it may lead to complication and even death. NIDDM is much more common than IDDM. It is often discovered by chance during routine blood sugar testing for other medical problem. It is typically gradual in onset and occurs mainly in the middle-aged and elderly. NIDDM is compatible with long survival with adequate treatment. Its clinical picture is usually complicated by the presence of other disease processes. Impaired glucose tolerance (IGT) describes a state describes intermediate-“at risk” group-between diabetes mellitus and normality. It can only be defined by the oral glucose tolerance test.
The Problem of Diabetes
(a) Mortality:
Diabetes is one of the leading causes of death in the developed western countries. For example in the USA, it is the fourth leading cause of death, and in other developed countries also it is a leading cause of death. The high rates for some developing countries like Trinidad are notable. In all the countries ketoacidosis is a significant cause of death and disability in diabetes along with severe hypoglycemia.
(b) Morbidity:
Diabetes is an “iceberg” disease, affecting more than 150 million people throughout the world. Diabetes prevalence in most adult populations is 2 to 5 per cent; in some populations, the rate is much higher. From 150 million at present the number is going to be more than double by 2025 and largest burden is going to be born by India and China. Diabetes prevalence is not the same throughout the world. IDDM effects between 1 in 500 children and 1 in 200 adolescents. In some populations IDDM is very uncommon, for example in Chinese, Japanese and American Indians (not the immigrants from India who has high prevalence of diabetes) who have retained their traditional life style. In some developing countries like Philippines the disease prevalence is increasing rapidly due to rapid changes in life style. The major causes of prolonged illness in diabetics are coronary heart disease, glomerulosclerosis (kidney disease), retinopathy (affects retina), gangrene of a lower limbs, neuropathy, stroke and cataract. Rates of disability are in general about 200 % to 300 % more in diabetics than in non-diabetics.
Tags: Hyperglycemia, Hypoglycemia, Type 1 or diabetes i, Type 2 or type ii
