Indian Write- Ups
| Management | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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| Interpretation of Blood Glucose Results | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| - Dr. Alka Ganesh | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Christian Medical College Hospital, Vellore. |
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| Introduction | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| The blood glucose level is a glimpse into a metabolic state of the diabetic patient. A comprehensive assessment however, would require several estimations, as also the use of other biochemical tests such as the glycosylated hemoglobin. The blood glucose level varies continuously, being dependent on the following factors - 1) site of sampling 2) the time interval from last meal and type of meal 3) exercise 4) type and dose of medication. A correct interpretation, followed through with appropriate action, presupposes and understanding of all these factors. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Blood Sample | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Venous blood is most convenient for laboratory estimation. The blood is usually collected in a fluoride-based anticoagulant, in order to cut short glycolysis ex vivo, and therefore, prevents a fall in the glucose level. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Capillary whole blood is most conveniently procured from the finger prick and ear lobe, or heel of the neonate, and is used for glucometer reading. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| It is important to know whether the glucose was measured in whole blood or in plasma, and the observed values should be compared with appropriate standards. Modern methods employed in the measurement of plasma glucose concentrations do so specifically without measuring other reducing substances and thus avoid false values e.g. enzymatic methods based on glucose oxidase. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Whole blood glucose concentrations are about 15% lower than plasma concentrations because the concentration of glucose is much lower in erythrocytes than in plasma. Glucose values are frequently measured with whole blood obtained by capillary finger prick and applied to reagent strip followed by visual inspection or use of a glucose meter. The glucose value in capillary blood is 7 or 8% higher than that in venous blood. Because the glucose level is measured immediately, consumption of glucose by erythrocytes is not a problem with these methods. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| SMBG-Self monitoring of blood glucose | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| This is one of the best methods of assessing glucose control with the patient in his normal work or home environment. It is convenient, simple and at times helps in reducing costly hospital admissions and laboratory visits. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| However, initially the patient must be informed and instructed in the use of a glucometer and the subsequent alterations that can be made in exercise/diet/ medication by the patient and/or to seek medical advice. It is also important to confirm the testing accuracy of the glucometer with laboratory correlation. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Fasting Glucose | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Fasting glucose is indicative of basal metabolic control in a diabetic, since meal-induced hyperglycaemia, does not confound the value. During fasting, the glucose needs of the body are met by glycogenolysis of stored hepatic glycogen (hepatic glucose output). This process is under the influence of glucagons, with insulin acting as a “brake” preventing excessive glucagon action. In severe diabetes, lack of insulin action results in unrestrained glucagons action on the liver giving rise to high fasting glucose. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| In proper diabetes management, fasting plasma glucose must be kept as close to base line (<140mg% plasma glucose) as possible so that the post meal excursions will take place from a lower “floor” thus achieving a lower “ceiling”. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Post Prandial Glucose | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| This can be done either one hour or two hours after a meal. One-hour value is of some use in screening for diabetes on a routine check. This will show up the highest post meal peak, and values above 160mg% can be considered suspicious, and warrant performance of a formal glucose tolerance test. In patients with a gastrojejunostomy, high one-hour values are expected because of rapid absorption. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| The two-hour postprandial plasma glucose value is taken as a measure of diabetic control. A value below 160mg% would indicate good control, 160-200mg% acceptable controls, and above 200mg, would be poor control. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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