Diabetes Classification : Types of Diabetes

Classification of Diabetes Mellitus

Diabetes Mellitus can be classified into mainly two types:

1)Type 1 Diabetes Mellitus (IDDM)

2)Type 2 Diabetes Mellitus (NIDDM)

IDDM and NIDDM classification is the old classification system of diabetes. IDDM stands for Insulin Dependent Diabetes Mellitus and NIDDM stands for Non Insuline Dependent Diabetes Mellitus.

Old classification system is not used because even type 2 diabetes patients can be insuline dependent if blood sugar level goes too high. So insuline dependency is not a convenient factor to classify diabetic patients. That is why, this is classified by the causative factors of diabetes and named type 1 and type 2. Type 1 diabetes is also known as juvenile onset diabetes according to its common target age group.

Type 1 diabetes : Type 1 diabetes is defined by an absolute requirement of exogenous insulin results from the autoimmune destruction of insuline - secreting pancreatic B cells. Type 1 diabetes is prone to ketoacidosis and exogenous insulin is required to prevent ketosis.

            Causes: 1) Environmental factors : Virus and food habit
                         2) HLA Antigen* (Human Leukocyte Antigen)

Both of these causes leads to autoimmune destruction* of Beta cell of pancreas that produce insuline.

Type 2 Diabetes : Type 2 diabetes is characterized by a relative insulin deficiency due to insulin secretory defect with insulin resistance. Ketoacidosis is absent. Most diabetic patient in the world has type 2 Diabetes.

             Cause: 1) Obesity or excess weight
                         2)Insuline resistance : Insuline is produced but not utilized
                         3) Genetic factors : Family history of diabetes

Comparison / Differences Between Type 1 and Type 2 Diabetes

 

Features	Type 1 Diabetes	Type 2 Dabetes
Dependency	Insuline dependent	Non insuline dependent or insulin independent.
Synonyms	Insuline dependent diabetes mellitus (IDDM) or, Juvenile onset diabetes	NIDDM (Non Insuline Dependent Diabetes Mellitus)
Target age group	Children or teenagers	Adults
Age of Onset	Usually below 20 years	Usually above 40 years
Insulin production	Body produces very little to no insulin.	Body produces little insulin or insulin is produced but it’s not utilized.
Role of genetic factor	May or may not responsible to cause type 1 diabetes	Definitely responsible for type 1 diabetes
Autoimmune B cell destruction	Present	Absent
Weight	Normal weight or non-obese	Usually excess weight or obese
Ketosis or Diabetic Ketoacidosis	Common	Rare
Plasma glucose level	High	Mild to moderate
Islet cell mass of pancreas	Severely reduced	Moderately reduced
Autoantibodies	Present	Absent
Family history of diabetes	Uncommon	Common
Occurrence	Rare. Only 5 to 10 % of the diabetic patient worldwide	90 to 95 % diabetic patients have type 2 diabetes
Treatment Plan	Sugar controlled healthy diet and regular insulin injection	Diet & blood glucose lowering drugs. Insuline injection in severe case only.

Other types of diabetes : (less common)

MODY : Mody or Maturity Onset Diabetes of the Young is caused by mutation in a specific gene called autosomal dominant gene. It causes to produce defective insuline. MODY is inherited from any of the parents. MODY differs from type 2 diabetes on the basis that, type 2 diabetes is associated with multiple gene defects and MODY is related to only one gene mutation. 

GDM or Gestational diabetes mellitus: Gestational diabetes causes to women during pregnancy with previous history of diabetes diagnosis. Insuline receptors do not function properly in gestational diabetes due to interference of pregnancy related factors such as human placental lactagen with insuline receptors. It generally occurs during third trimester of pregnancy. It is well established  that whether it is a natural phenomenon or a disease because up to 15% pregnant woman suffer from gestational diabetes. Sometimes gestational diabetes can lead to type 2 diabetes if this condition persists after pregnancy.

Idiopathic diabetes : Idiopathic diabetes is closely related to type 1 diabetes. Type 1 diabetes is caused by autoimmune destruction of pancreatic beta cells but idiopathic diabetes has no known cause. It shows symptoms like diabetic ketoacidosis which is common in type 1 diabetes but there is no solid evidence of autoimmune cell destruction. Idiopathic diabetes can be both insuline dependent and insuline independent. 

LADA or Late Autoimmune Diabetes for Adults: Lada is a type of diabetes that has similarity with both type 1 and type 2 diabetes. The cause of this type of diabetes is autoimmunity like type 1 diabetes and it is diagnosed at adult age like type 2 diabetes. For similarity of both type of diabetes, it is known as type 1.5 diabetes. It is often misdiagnosed as type 2 diabetes. 

Diabetes incipidus : Diabates incipidus is not associated with glucose metabolism or insuline. It is a condition caused by lack of vasopressin or anti diuretic hormone (ADH) by posterior pituitary gland. It may also caused by defect in the nephrons of the kidneys where receptors of this hormone are present. Due to lack of anti diuretic hormone action , diuresis or urination occurs more frequently which is the only similarity of diabetes incipidus with diabetes mellitus.


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*HLA antigen : Consists of large number of genes related to human body's immune system.


*Autoimmune destruction : Pathogens (bacteria, virus) or external body compounds are destroyed by our body's immune system. But sometimes specific cells of our body organs are destroyed by our  immune system due to some disorder. This self destruction of body cells by our own immune system is referred to as autoimmune destruction.