Investigations

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SCREENING FOR  DIABETES

Adults more than 45 years of age should be screened for diabetes. If their blood glucose is normal initially, then they should be investigated at 3-year intervals.

People under 45 years of age should also be screened if:

  • they have impaired glucose tolerance when previously tested for diabetes.
  • they are overweight (more than 20% of the Ideal Body Weight) or have a Body Mass Index (BMI) above 22 for Indians and 27 for Non-Indians.
  • they have a family history of diabetes.
  • their blood pressure is 140/90 millimeters of mercury (mmHg) or more.
  • they have abnormal blood lipid levels, such as high density lipoprotein (HDL) cholesterol less than 35 mg/dL (or an HDL value less than 25% of total cholesterol) or triglycerides greater than 250 mg/dL.

Mothers under the age of 45 years need to be screened if there has been a history of diabetes during pregnancy or if one has delivered a baby weighing more than 4.1 kg (9 lbs).

Diagnosis of Diabetes bloodtest Diagnosis is made in the presence of symptoms confirmed by at least two positive results from the following tests:

  • A random plasma glucose level* of 200 mg/dL or more (blood samples can be taken any time of the day).
  • A fasting plasma glucose value* of 126 mg/dL or greater after a person has fasted overnight for 8-10 hours (no bed tea). Blood sample is to be taken before 9 a.m. since stress hormone levels rise during the later part of the day, elevating the blood glucose levels even though you may be fasting.
  • Plasma glucose value* of 200 mg/dL or more in the blood sample, taken 2 hours after a person has consumed 75 grams of glucose dissolved in 300 ml of water. Very often, the glucose is replaced by a meal and the blood sample taken thereafter (post-prandial) has no diagnostic value as the blood glucose level varies depending on the meal taken.
  • * It is important to note that plasma glucose levels are 10-15% higher than venous blood glucose levels.

Note :

Testing glucose levels in the urine has little  value in assessing the control of diabetes.

Monitoring Diabetes Control

  • Blood Glucose testing : The management plans should be aimed to maintain pre-prandial (before meals) blood glucose levels at 80-120 mg/dl and post-prandial blood glucose (2 hours after meals) at less than 180 mg/dl.
  • Urine test : Urine test for glucose has little diagnostic value. However, presence of glucose in urine gives a rough estimate of increased blood sugar levels ( usually, glucose starts appearing in the urine when the blood glucose levels exceed 180 mg/dl). Moreover, urine test for ketones is diagnostic for ketoacidosis (a serious complication of Type 1 Diabetes).
  • Glycosylated hemoglobin test (Hb A1c test) : It is a test with a memory which narrates the blood glucose control for the past three months. Normal values should be around 3.9 – 6.9 %. Statistical studies have shown a very high correlation of Glycosylated hemoglobin with the progress of diabetes and its complications.
  • Serum fructosamine assay is preferred over glycosylated hemoglobin in certain conditions like
    • Abnormal hemoglobin diseases
    • Hemolytic disorders
    • Pregnancy

The test indicates blood glucose levels for the preceding 2 weeks. Normal levels are 1.5 – 2.4 mmol/L when serum albumin is 5g/dl.

Other Investigations

Your Doctor may also suggest the following tests to determine the damaging effects of Diabetes on various organs in the body. This will ensure early detection of your problems so that appropriate preventive measures could be taken before hand.

  • Lipid profile: Diabetes patients frequently have abnormal lipid profile. Increased levels of blood lipids tends to hasten the process of thickening and narrowing of blood vessels hampering the blood supply to various organs in the body (particularly brain, heart, extremities especially lower limbs). Thus, lipid profile helps to assess the risk of coronary heart disease (CHD), stroke and peripheral vascular disease. It includes serum cholesterol (normal value: <200 mg/dl), LDL cholesterol (normal value: <130 mg/dl), HDL cholesterol (normal value: >35 mg/dl), VLDL cholesterol (normal value: <35 mg/dl),  triglycerides, (normal value: <165 mg/dl) LDL: HDL ratio  (normal value: <3.55), total cholesterol: HDL ratio  (normal value: <5) and Apolipoprotein A-1: Apolipoprotein B ratio (normal value: >1.35).ECG, ECHO and TMT: Coronary heart disease is the most common and costly vascular complication of Diabetes. These tests may detect the coronary heart disease at an early stage. Electrocardiograph (ECG) records the electrical changes in the heart through electrodes placed on the body. ECG done at rest, may be normal. Since the likelihood of detecting the typical changes in ECG are more during the episode of chest pain, immediate ECG in such cases is essential. Treadmill test (TMT) involves continuous recording of ECG is done before, during and  after exercise using a treadmill or bicycle ergo meter. This test can also be used to assess the severity of coronary artery disease. Echocardiography (ECHO) is done with the help of a scanner which uses sound waves to get a picture of the heart. Simply speaking, it is the ultrasound of the heart. It may be done at rest and after exercise.
  • Urine test for microalbuminuria: Detection of a minute quantity of albumin (a type of protein) in urine (microalbuminuria) is the first indication of kidney damage in Diabetes. This test is very important because at this stage preventive measures can delay or even reverse the kidney damage. In certain cases, measurement of protein in 24 hour urine samples  (normal value: <150 mg/day) may be advised.
  • Serum Creatinine: Uncontrolled Diabetes may adversely affect the kidney functions. Serum Creatinine  (normal value: 0.6-1.5 mg/dl) is done to assess the functioning of kidneys. For a more detailed analysis, your doctor may advise you to go in for renal function tests which may include Blood Urea (normal value: 20-40 mg/dl), Blood Urea Nitrogen (normal value: 8-20 mg/dl), Serum Electrolytes such as Sodium (normal value: 135-145 mEq/dl), Potassium (normal value: 3.5-5.0 mEq/dl), Chloride (normal value: 98-106 mEq/dl), Total Serum Proteins (normal value: 5.5-8.0 g/dl) and Serum Albumin (normal value: 3.5-5.5 g/dl).
  • Fundoscopy (eye examination): Uncontrolled diabetes may damage the inner layer of eye (known as retina). Eye check-ups (Fundoscopy with dilated pupil), at least once a year is essential to detect retinal damage (retinopathy) in Diabetes patients.