Diabetes Mellitus (DM)

Blue circle for diabetes[1]

Diabetes mellitus is a common metabolic disorder of multiple etiology, characterized by chronic hyperglycaemia with disturbances of carbohydrate, fat and protein metabolism due to defects in insulin secretion, insulin action, or both. There are four main types of diabetes mellitus: type 1 diabetes mellitus, type 2 diabetes mellitus, gestational diabetes and other specific types (genetic syndromes, pancreatitis, cystic fibrosis, exposure to certain drugs, etc.).


Patients with type 1 diabetes mellitus usually present with classic acute symptoms of hyperglycemia. These include:

  • Polyuria (due to osmotic diuresis when blood glucose level exceeds renal threshold)
  • Thirst (as a consequence of loss of fluids and electrolytes by osmotic diuresis)
  • Postural hypotension (due to reduction of plasma volume by osmotic diuresis)
  • Loss of weight (due to depletion of glycogen stores by glycogenolysis and triglyceride stores by lipolysis; and the reduction of muscle mass as a consequence of the diversion of amino acids for gluconeogenesis)
  • Blurring of vision (because of the exposure of the lens and retina to hyperosmolar fluids)

Around 25% of the cases of diabetes mellitus present with the acute complication of ketoacidosis.

In contrast, most of the patients of type 2 diabetes mellitus do not have acute symptoms. The disease may be present for an average of 4 to 7 years before it is detected. The patients have a history of increased urination and thirst but most are asymptomatic initially. The presenting complaints of the patients include lack of energy, delayed wound healing, visual blurring and fungal infections such as pruritis vulvae or balanitis [5].

In addition, the following complications may be the initial presenting feature in chronically undetected cases.


The following investigations are helpful in establishing the diagnosis of diabetes mellitus.

  • Random blood sugar: Diabetes is labelled if the random blood sugar is found to be greater than 200 mg/dL. It is not sufficient for diagnosing diabetes and fasting blood sugar should always be checked subsequently.
  • Fasting blood sugar: Diabetes is confirmed if the fasting blood sugar is more than 126 mg/dL on more than one occasion.
  • Glucose tolerance test: Glucose tolerance test is required for the confirmation of diabetes when the fasting blood sugar is more than normal but less than the diabetic range.
  • Glycosylated hemoglobin: Level of glycosylated hemoglobin reflects the state of glycemia over the preceding 8 to 12 weeks.
  • Serum fructosamine: Serum fructosamine reflects the state of glycemic control for the preceding 2 weeks.


The treatment methods available for diabetes mellitus include:

  • Diet alone
  • Diet and insulin
  • Diet and oral hypoglycemic drugs


Around 60% of the patients can be treated adequately with diet alone. A proper diet regimen should be prepared based upon the age, sex, weight and caloric requirements of the patient. Readily absorbable carbohydrates such as sugars should be avoided. Non-nutritive sweeteners such as asparmate, saccharine or sucramate should be used if needed.

Oral hypoglycemic drugs

Oral hypoglycemic agents are useful for the treatment of type 2 diabetes mellitus. A wide number of oral hypoglycemic agents are available. They are prescribed individually or in combinations according to the patient. Common oral hypoglycemic agents include sulphonylureas (e.g. glimepride and glipizide), biguanides (e.g. metformin), alpha glucosidase inhibitors (e.g. acarbose and migitol), thiazolidinedions (e.g. pioglitazone and rosiglitazone), D-phenylalanine derivatives (e.g. nateglinide) and insulin stimulators (e.g. repaglinide) [7][8].


Insulin is used in the treatment of all patients of type 1 diabetes mellitus and in those patients of type 2 diabetes whose hyperglycemia is not controlled by diet and oral hypoglycemic agents. Various preparations of insulin are available and are selected according to each patient.


Diabetes mellitus is a chronic disease that disturbs the quality of life of all the patients [4]. The patients are forced to take daily insulin injections and/or oral hypoglycemic drugs. Lifestyle and diet modifications also become essential. However, with early diagnosis and proper control of the disease, the risk of development of associated diseases and complications can be reduced and the patients enjoy a life expectancy that approaches those without the disease. Untreated diabetes mellitus is associated with a high mortality and morbidity rate.


Diabetes mellitus may be primary or secondary.
Primary diabetes mellitus has two types [2].

  • Insulin dependent diabetes mellitus (Type 1)
  • Non-insulin dependent diabetes mellitus (Type 2)

Type 1 diabetes mellitus usually results from an autoimmune disease process. It is associated with a positive family history. The child of a patient having type 1 diabetes has a greater risk of developing the disease. The risk is greater with diabetic father as compared to the diabetic mother. There is around 30 to 35% concordance in monozygotic twins. 95% of the patients carry HLA-DR3, HLD-DR4 or both genes. Infection with coxsackievirus B4

Type 2 diabetes mellitus has a 100% concordance in identical twins, implying a much stronger genetic association. Around 25% of the patients have a first degree relative suffering from this disease. Overeating combined with obesity acts as a diabetogenic factor.


Type 1 diabetes mellitus is the most common metabolic disease in childhood. It is present in around 1 in every 500 child or adolescent.

Type 2 diabetes mellitus is very common worldwide, particularly the US because of the high caloric diet. Its incidence is on the rise and it is said that type 2 diabetes is rapidly becoming a global “epidemic”. It is estimated that around 552 million people worldwide will be suffering from it by the year 2030.

Sex distribution
Age distribution


Type 1 diabetes mellitus is caused by an autoimmune process in which there is lymphocytic infiltration and subsequent destruction of the beta cells in the pancreas. These cells are responsible for the production of insulin and their destruction causes the level of insulin to fall leading to hyperglycemia.

In type 2 diabetes mellitus, there is both reduced secretion of insulin as well as insulin resistance in the peripheral tissues [3]. As a result, hyperglycemia develops.


There is no effective preventive measure against type 1 diabetes mellitus as it is an autoimmune disease that occurs early in childhood.

Type 2 diabetes mellitus can be prevented by adopting a healthy lifestyle. Eating a healthy diet, avoiding overeating, controlling obesity and performing daily exercise greatly reduce the risk of development of type 2 diabetes mellitus [9] [10].


Diabetes mellitus is a clinical syndrome that is characterized by chronic hyperglycemia along with disturbances in the metabolism of carbohydrates, lipids and proteins [1]. It is of two main types, type 1 and type 2 diabetes mellitus. The former is also referred to as insulin dependent diabetes mellitus while the latter is also known as non-insulin dependent diabetes mellitus.

Patient Information

Diabetes mellitus is a disease in which the level of sugar in the blood is raised. It is of two types, one usually affecting people since childhood and the other appearing late in adulthood. Diabetes is associated with many diseases and complications and should be diagnosed and treated early to ensure better expectancy and quality of life.


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Media References

  1. Blue circle for diabetes, Public Domain