Estimation of blood Sugar concentration

Blood sugarThe blood sugar concentration or blood glucose level is the amount of glucose (sugar) present in the blood of a human or animal. The body naturally tightly regulates blood glucose levels as a part of metabolic homeostasis. The mean normal blood glucose level in humans is about 5.5 mM (5.5 mmol/L or 100 mg/dL, i.e. milligrams/deciliter) Blood sugar levels outside the normal range may be an indicator of a medical condition. A persistently high level is referred to as hyperglycemia; low levels are referred to as hypoglycemia

Homeostasis of blood glucose

Abnormality in blood sugar levels

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•Diabetes mellitus, is a group of metabolic diseases in which a person has high blood sugar, either because the pancreas does not produce enough insulin, or because cells do not respond to the insulin that is produced. This high blood sugar produces the classical symptoms of polyuria (frequent urination), polydipsia (increased thirst) and polyphagia (increased hunger).

There are two main types of diabetes mellitus (DM)1. Type 1 DM results from the body's failure to produce insulin, and

currently requires the person to inject insulin. This form was previously referred to as "insulin-dependent diabetes mellitus" (IDDM) or "juvenile diabetes".

2. Type 2 DM results from insulin resistance, a condition in which cells fail to use insulin properly,. This form was previously referred to as non-insulin-dependent diabetes mellitus (NIDDM) or "adult-onset diabetes"

B) Low blood sugar: hypoglycemia

• If blood sugar levels drop too low, a potentially fatal condition called hypoglycemia develops. Symptoms may include lethargy, impaired mental functioning; irritability; shaking, twitching, weakness in arm and leg muscles; and loss of consciousness. Brain damage is even possible.

Estimation of blood glucose by Glucose oxidase method

•Principle:Glucose oxidase is an enzyme . Glucose oxidase catalyze the oxidation of Beta D- glucose present in the plasma to D glucono -1 ,5 - lactone with the formation of hydrogen peroxide; the lactone is then slowly hydrolyzed to D-gluconic acid. The hydrogen peroxide produced is then broken down to oxygen and water by a peroxidase enzyme. Oxygen then react with an oxygen acceptor such as ortho toluidine which itself converted to a colored compound, the amount of which can be measured calorimetrically.

Principle:

• Glucose oxidase

• Serum ------------→ D glucono -1 ,5 - lactone +H2O2

• Beta D- glucose

• D glucono -1 ,5 - lactone ------------→ D-gluconic acid.

• peroxidase enzyme

• H2O2 ------------→H2o+ O2

• O2 +- ortho toluidine -----------→ colored compound

ProcedurePipette into identified test tube

Blank Standard Assay(sample)

Reagent 1mL 1mL 1mL

D.W 10ML --------- -----------

Standard ---------- 10ML ------------

Serum ------- ----------- 10ML

Mix. Let stand for 10 min. at 37c .read absorbance at 500nm

Calculation

CS =100mg/dl

Concentration of Glucose (mg/dl)=(Abs.Assay/Abs.Standard)×Standard concentration