Diabetes Mellitus: Definition and Classification

In this post I am gonna discuss about Diabetes mellitus.

Diabetes Mellitus:

It is a chronic metabolic disorder characterized by a high blood glucose concentration (hyperglycemia) and disturbances of carbohydrate, fat and protein metabolism caused by deficiency of insulin in the body or resistance to the action of insulin.

• DM affects about 5-8% of population
• In DM fasting plasma glucose > 7.0mmol/L
• DM is confirmed by GTT

Symptoms:

3P

• Polyphagia
• Polydypsia
• Polyuria

Treatment:

3D

• Discipline
• Diet
• Drugs

Complication of uncontrolled DM:

I. Micro vascular:

§  Retinopathy

§  Nephropathy

§  Neuropathy

§  Cataract

II. Macro vascular: Atherosclerosis following dyslipidemia leading to IHD and CVA

When the renal threshold for glucose reabsorption is exceeded, glucose come into urine (glycosuria), causes osmotic diuresis ( polyuria), which in turn result in dehydration, thirst and increased dinking tendency ( polydypsia) 

Types of Diabetes Mellitus:

1. IDDM (Type -1) Insulin dependent diabetes mellitus: It is severe form of diabetes mellitus, it occurs in juvenile period i.e. child & younger. Here, circulating insulin is virtually absent because β cell are damaged & β cell failed to secrete enzyme.

Criteria:

• Autoimmune type is commoner than idiopathic type
• Age <30yrs
• Abrupt onset
• Not obese when they first develop symptom
• Polyuria, polydipsia, polyphagia
• Due to absolute deficiency of insulin resulting form autoimmune destruction of beta cell
• Treatment – diet control and insulin
• Without insulin the treatment of such patient will die ultimately with diabetic ketoacidosis
• Diabetic ketoacidosis only occur in type I

2. NIDDM (Type-2) or maturity onset DM: It is milder form of diabetes, it occurs in adult. Here circulating insulin level is present but insufficient to reduce blood sugar level.

Criteria:

• Have genetic predisposition – about 90-95% sufferer have family history
• Age > 40
• Gradual onset
• Usually obese
• Usually asymptomatic
• Due to both by insulin resistance and impaired insulin secretion
• Treatment:

o    Initially diet control alone

o    Diet control + oral hypoglycemic drug

o    1/3^rd patient require insulin

§  Ketoacidosis is usually absent

3.  Type – 3 mellitus:

i. Drugs –

§  Corticosteroids

§  Thiazide diuretics

§  Phenytoin

ii. Some non pancreatic disease –

§  Acromegaly

§  Cushing’s syndrome

§  Pheocromocytoma

§  Hyperthyroidism

4. Type 4 DM:

• It is known as gestational diabetes (GDM)

GDM is defined as any abnormality in glucose level for the 1^st time during pregnancy