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Diabetes Mellitus - A Clinical Biochemist's View

Dr. Seema Garg M.D. (Biochemistry) Medical Officer

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Diabetes Mellitus (DM) a household entity in today’s world, is one of the most challenging health problem of the 21st century.It has catapulted itself from a rare disease at the beginning of the century to the 4th commonest cause of mortality.The prevalence of diabetes is increasing worldwide.

The need of the hour is that the authorities as well as the public should awaken from their slumber and take a view of the delicate situation we are in right now, and prevent further progress on this road to diabetes.

To evaluate the risk factors it is essential that the patient undergo a careful history and detailed medical examination along with certain laboratory tests. Such tests include measurement of blood glucose, serum lipids- total cholesterol, HDL cholesterol, LDL cholesterol, Triglycerides, etc. and very important, but often overlooked test is for (micro and macro) albumin in urine. The importance of this test of urine cannot be overemphasized in today’s world in a diabetic care clinic setting.

Diabetes mellitus is a Hormono-metabolic disorder characterized by elevated circulating blood glucose levels resulting from defects in insulin secretion, action or both. Diabetes Mellitus has been classified as:

1. Type 1 diabetes (formerly known as insulin dependent diabetes mellitus), is a disease characterized by a total failure to produce insulin.

2. Type 2 diabetes (formerly called non-insulin dependent diabetes mellitus) usually arises because of insulin resistance combined with relative insulin deficiency. It typically occurs in middle age, overweight and sedentary persons, with a family history of DM.

3.Other specific types

4. Gestational Diabetes Mellitus (GDM) is defined as any degree of glucose intolerance with onset or first recognition during pregnancy. It generally manifests around 24-28 weeks of pregnancy.

Type 2 diabetes is the commonest form of diabetes constituting 90% of the diabetic population in any country.

For labeling a person as having DM, the criteria used at present, are according to the guidelines issued by the Expert Committee on the Diagnosis and Classification of Diabetes Mellitus. A person is diagnosed as having DM, if he fulfils any one of the following conditions:

1) Symptoms of DM plus a casual plasma glucose concentration of >200 mg/dl.(Casual is defined as any time of the day without regard to time since last meal. The classic symptoms of DM include repeated urination, excessive thirst and unexplained weight loss.)

2) Fasting plasma glucose >126mg/dl.(Fasting is defined as no caloric intake for at least 8 hours).

3) 2 hour plasma glucose >200 mg/dl during an oral glucose tolerance test (OGTT-This test employs a sample in the fasting state followed by a glucose load of 75 grams dissolved in 250 ml of water, to be taken by mouth, and the next sample be taken 2 hours after consuming this).

If abnormal results are obtained in any of these tests they should be confirmed by repeating on another day and only then the diagnosis of DM should be served to the individual.

The terms “Impaired Fasting Glucose” (IFG) and “Impaired Glucose Tolerance” (IGT) refer to a metabolic state intermediate between normal glucose metabolism or homeostasis and diabetes, also referred to as pre-diabetes.The persons with IFG or IGT are those whose glucose levels do not meet the criteria for DM , but are too high to be considered as altogether normal. IGT is by itself not a benign condition. It’s prevalence varies from 2-16.4 % in different populations. The rate of conversion of IGT to DM is from 2.5 – 5 % per year. The risk of conversion is higher in patients with high plasma glucose levels at the time of diagnosis of IGT, increasing age, obesity- more so central obesity, recurrent infection, etc. Risk of coronary artery disease is higher in IGT patients. Diet modification and exercise are the mainstay in the management of subjects with IGT. Several different studies have demonstrated that the progression of IGT to DM is delayed. This classification divides the population into three categories when we use fasting plasma glucose (FPG) levels for diagnosis:

  • FPG < 110 mg/dl = Normal fasting glucose;
  • FPG from 110-125 mg/dl = IFG
  • FPG 126 mg/dl or above = provisional diagnosis of DM, (diagnosis to be confirmed)

The corresponding categories when the OGTT is used are;

  • 2-hour postload glucose(PG) upto139 mg/dl = normal glucose tolerance
  • 2-hour PG 140-199 mg/dl =IGT
  • 2-hour PG 200mg/dl or above = provisional diagnosis of DM (diagnosis to be confirmed).

With diet and exercise therapy, even medicines may be used.


M.D. (Biochemistry) Medical Officer, Civil Hospital, Hoshiapur.

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