Diabetes Mellitus , its Types(1,2) & Modern Classification

Diabetes Mellitus , its Types(1,2) & Modern Classification

what is Diabetes Mellitus

Diabetes also called diabetes mellitus When glycosuria is detected and hyperglycaemiais established, a chronic metabolic disorder known as diabetes mellitus is indicated. 

It is a condition which is characterised by disturbances in carbohydrate. lipid and protein metabolism.

Diabetes Mellitus , its Types(1,2) & Modern Classification

•  Hypergly-caemia and glycosuria indicate the major metabolic lesion in carbohydrate metabolism, accompanied by metabolic disturbances in protein (gluconeogenesis) and lipids (ketosis and hypercholesterolaemia).

• The presence of hyperglycaemia and renal glycosuria with an osmotic diuresis (polyuria) eventually will lead to dehydration and its associated polydipsia (increased thirst). 

• Hyperglycaemia is sustained by the processes of glycogenolysis and gluconeogenesis which enhance the production of more glucose. 

Formation of ketone bodies 

Acetoacetic acid, beta-hydroxybutyric acid and acetone are collectively known as ketone bodies or ketones. When any of these substances is detected in blood, the condition is referred to as ketoacidosis or ketonaemia; and when found in urine, it is called ketonuria.

• When the intake of glucose is insufficient, as in starvation, or when glucose metabolism is impaired due to lack of insulin as in the case of untreated or uncontrolled diabetes, the body obtains its energy by breaking down fats to fatty acids.

• This increase in fat metabolism leads to the production of acetyl coenzyme A. The two carbon fragments in this enzyme condense to form the ketone bodies. Ketoacidosis is a potentially fatal complication of diabetes mellitus.

Types of Diabetes Mellitus There are two types of the conditions known as primary diabetes:

1. Maturity-onset (adult type)

2. Growth onset (juvenile or child diabetes)

The course of diabetes mellitus runs in four stages:

1. Prediabetes The prediabetic stage is the period from birth until the first evidence of diabetes emerges. 

2. Suspected diabetes When an individual displays abnormal glucose tolerance test (GTT) result, or shows symptoms of diabetes under stressful conditions such as obesity, pregnancy, trauma or infections, the condition is referred to as suspected diabetes. 

3. Chemical or latent diabetes When a patient who is not under any stress and with no signs or symptoms of disease, displays an abnormal GTT result, or fasting hyperglycaemia, he/she is said to have chemical or latent diabetes. 

4. Overt diabetes With overt diabetes, symptoms of polyuria, polydipsia and weight loss are often linked to fasting hyperglycaemia and glycosuria.

Modern Classification of Diabetes Mellitus

National Diabetes Data Group has proposed a classification for hyperglycaemic disorders which is outlined below:

1. Idiopathic diabetes mellitus

(a) Insulin dependent diabetes mellitus (IDDM Type I) The individuals in this category produce very little insulin. The patient is acutely ill with severe hyperglycaemia at the time of diagnosis. 

• Satisfactory control of blood sugar is obtained with insulin treatment. About 10 per cent of diabetes mellitus cases belong to this category. 

(b) Non-insulin dependent diabetes mellitus (NIDDM Type2) This is the most common form of diabetes mellitus (80-90%). Most patients with this form of diabetes are relatively deficient in insulin and have mild hyperglycaemia. 

• Obsesity is commonly associated with NIDDM and decrease in obesity brings about reduction in hyperglycaemia in most cases. Some persons with NIDDM may be non-obese. 

• A small percentage of NIDDM patients may require insulin injections or an oral hypoglycaemia agent to control hyperglycaemia. 

2. Gestational diabetes mellitus (GDM) In these cases, glucose intolerance is discovered for the first time during pregnancy. Such a woman is at high risk for foetal morbidity and should be promptly treated. 

3. Impaired glucose tolerance (IGT) Persons with IGT are borderline cases with slightly raised glucose levels without overt hyperglycaemia. Such cases may later develop diabetes mellitus or revert to normal levels. Generally, they are at high risk of development of cardiovascular disease. 

4. Previous abnormality of glucose tolerance (Prev. AGT) Persons in this category have a history of diabetes but have reverted to normal levels. e.g. those with GDM or obese NIDDM. 

5. Potential abnormality of glucose tolerance (Pot. AGT) Persons at a more than average risk of developing diabetes belong to this category, e.g., child of parents with NIDDM. 

6. Glucose intolerance associated with other disorders Hyperglycaemia due to underlying disorders such as chronic pancreatitis, Cushing's disease, and acromegaly are included in this category.