Glucose Estimation PDF

Glucose Estimation The body’s sources of glucose are dietary carbohydrates and endogenous production by glycogenolysis (release of glucose stored as glycogen) and gluconeogenesis (glucose synthesis from non-carbohydrate sources, for example, lactate, glycerol, pyruvate, and glucogenic amino acids)....

Glucose Estimation The body’s sources of glucose are dietary carbohydrates and endogenous production by glycogenolysis (release of glucose stored as glycogen) and gluconeogenesis (glucose synthesis from non-carbohydrate sources, for example, lactate, glycerol, pyruvate, and glucogenic amino acids). Blood glucose concentration depends on the relative rates of influx of glucose into the circulation and its utilization. Hormones involved in glucose homeostasis: The two most important hormones in glucose homeostasis are insulin (decreases glucose level) and glucagon (increases glucose level). Insulin is a 51 amino acid polypeptide, secreted by the β-cells of the pancreatic islets of Langerhans in response to a rise in blood glucose concentration. It is synthesized as a prohormone, proinsulin. This molecule undergoes cleavage prior to secretion to form insulin and C-peptide. 1 Other hormones that cause an increase in glucose levels in the blood are: 1- Adrenaline. 2- Growth hormone. 3- Glucocorticoids. 4- Cortisol. From beta cells of pancreas From alpha cells of pancreas C-Disorders in hormonal circulation: 1- Hyperglycemia: it is the case of increasing blood glucose level. 2 a- Type-1 diabetes mellitus (insulin dependent diabetes mellitus(IDDM)): Individuals at the risk of this type due to autoimmune pathological process occurring in the pancreatic islets. Treatment: Injection of insulin to patients will be a solution b- Type-2 diabetes mellitus (non-insulin dependent diabetes mellitus(NIDM)): Many patients have body cells with a decreased response to insulin known as insulin resistance. Treatment: 1. Exercises, weight loss, diet control. 2. Improve cell’s sensitivity to insulin so it uses insulin more effectively. 3. Limiting liver’s ability to make and release sugar (inhibit glycolysis and gluconeogenesis). 4. blocking the action of enzymes in the intestines that break down carbohydrates and inhibit intestinal glucose absorption and increasing peripheral glucose uptake and utilization. 5. Insulin therapy: Some people who have type2 diabetes need insulin therapy. In the past, it was used as the last resort, but today it may be prescribed sooner if blood sugar targets aren’t met with lifestyle changes and other medications. c- Gestational diabetes mellitus (GDM): Glucose Insulin secretion Glycerol Triglyceride During pregnancy, the placenta makes hormones like progesterone and estrogen that cause glucose to build up in your blood instead of being absorbed by the cells. Usually, mother’s pancreas can send out enough insulin to handle it. But if 3 mother’s body can’t make enough insulin or stops using insulin as it should, her blood sugar levels rise, and she gets gestational diabetes. Upon delivery of the fetus the glucose level turns to normal again and women with GDM may continue to be hyperglycemic after delivery and may be determined to have in fact type II diabetes. For the fetus of uncontrolled GDM mother, the increased glucose level in the mother’s blood will affect him in which the level of its insulin secretion will increase, to overcome the high glucose concentration reaching him from the mother so increased insulin secretion will increase the size of the fetus and becomes overweight due to increased storage of glucose, (as a glycogen and triglycerides), and it will suffer from hypoglycemia due to increased insulin secretion. 2-Hypoglycemia: it is the case of decreasing blood glucose level. 1- There is no glucose source. 2- Increased insulin secretion due to tumors (Tumor in pancreas) 3- Disorders in glycogen synthesis (Glycogenolysis will not occur) 4- Severe malnutrition. 5- Severe starvation, which will affect the stored glycogen and fats to very low levels. D-Diagnosis of diabetes: 1- Blood sample: Fluoride tubes is used as fluoride inhibits enolase enzyme which inhibits glycolysis. a- Random blood glucose (RBG): it is collected at any time (70 – 140 mg/dl) b- Fasting blood glucose (FBG): it is collected after 6-8 hrs. of fasting (70 – 110 mg/dl) water is allowed. Note: - if fasting increased more than 8 hrs. Glucagon will start to increase the glucose level in blood by breaking down of glycogen. c- Postprandial blood glucose (PPG): it is collected after 2 hrs. of meal ingestion (≤140 mg/dl), Note: if the amount of meal ingested is lower than the amount of insulin produced the glucose level will be low and if the patient drinks a sweet juice or eat more carbohydrates than allowed it will increase the glucose concentration in the test, he should eat small amount of the carbohydrates and not to drink a sweet juice before performing the test. 4 2- Urine sample: - Renal threshold: is the concentration of a substance dissolved in the blood above which the kidneys begin to remove it into the urine (Affinity of the kidney to absorb glucose). When the blood glucose level exceeds about 160–180 mg/dl, (the proximal tubule becomes overwhelmed and begins to excrete glucose in the urine. Some normal persons have low renal threshold (110mg/dl) so glucose appears in urine and he is not suffering from any diseases. a- A urine test strip or dipstick is a basic diagnostic tool used to determine pathological changes in a patient's urine in standard urinalysis. Ketones is significant in urine when cells don't get enough glucose, your body burns fat for energy instead. This produces a substance called ketones, which can show up in your blood and urine, High ketone levels in urine may indicate diabetic ketoacidosis (DKA), a complication of diabetes (sever uncontrolled diabetes mellitus) that can lead to a coma or even death, It can also appears during prolonged fasting as physiological case. Ketones in urine test can prompt you to get treatment before a medical emergency occurs. Occurs mainly with type- 1 diabetes mellitus, no insulin that help cells to uptake glucose so, cells start to break fatty acids to get ATP and ketone bodies produced as byproducts like acetone which excreted in the urine. Can not depend on urine glucose level only as it may give: a- False positive result: glucose appears in urine and has normal range in blood at the same time due to glucose low renal threshold of the kidney where glucose can appear in the urine at 110 mg/ dl in the blood. b- False negative result: no glucose in the urine but the patient is diabetic. Ex, patient has 150 mg/ dl in the fasting blood glucose test and has no glucose in the urine. 3- Oral glucose tolerance test (OGTT): What is an OGT test? The test is used to determine whether the body has difficulty metabolizing intake of sugar/carbohydrate, the patient is asked to take a glucose drink, and their blood glucose level is measured before and at intervals after the sugary drink is taken. How is the test performed? Before the test, you will be asked not to eat, or drink certain fluids, for up to 8 hours before the test. You may be asked not to take certain 5 medications in the lead-up to the test, but only if these would affect the test results. For the test itself, you will first have blood taken to measure your blood glucose level before the test. The next stage is to take a special weight of glucose dissolved in water according to the weight of the person. Further blood samples will then be taken at intervals of 30, 60, 90, and 120 minutes. Then draw a curve between absorbance and concentration from which you can detect if the patient is diabetic or prediabetic patient. 200 4- Glycemic control tests: a- HbA1c hemoglobin A1c (Glycated/Glycocylated/Glycohemoglobin ) test: Measures the amount of blood glucose attached to hemoglobin. Hemoglobin is the part of your red blood cells that carries oxygen from your lung to the rest of your body. An HbA1c test shows what the average amount of glucose attached to hemoglobin has been over past three months. It’s a three-month average because that typically how long a red blood cell lives. Used to help in diagnosis of diabetes, pre-diabetes, and aid in treatment decisions, also in monitoring diabetic patient. Diagnosis: A1C Level Normal below 5.7. 6 Prediabetes 5.7 to 6.4. Diabetes 6.5 percent or above. In monitoring, if A1c is less than 7% this indicates good glucose control and lower risk of diabetic complications for majority of people with diabetes. Note: If you have anemia or other type of blood disorder, an Hb1Ac test may be less accurate for diagnosing diabetes. As in hemolytic anemia RBC´S are disroyed in high rate than normal so, Hb decrease and cannot depend on HbA1C. In newborn (before 6 month): normally has high level of RBC´S so, high level of HbF (fetal Hb) cannot depend on HbA1C in neonatal diabetes mellitus. In these cases, we can use another glycemic control test as fructosamine test. b- Fructosamine test (Glycated serum protein GSP or Glycated albumin test): Fructosamine is a compound that is formed when glucose combines with protein by non-enzymatic binding between glucose and serum proteins usually albumin. This test measures the average blood glucose level over 2-3 weeks prior to the test is performed. Help in monitoring your blood glucose (sugar) levels over time if you have diabetes, especially if it is not possible to monitor your diabetes using hemoglobin A1c test; to help to determine the effectiveness of changes to your diabetic treatment plan that might include changes in diet, exercise, medication. Note, if a person suffers from disease that effect on albumin synthesis such as liver disease so, cannot perform fructosamine test. 5- C-peptide test (Connecting peptide insulin, Proinsulin C-peptide): C-peptide is a short 31-amino-acid polypeptide that connects insulin's A-chain to its B-chain in the proinsulin molecule.so it is released from the pancreas at the same time insulin is released, and in about the same amount. 7 So, a C-peptide test is used to determine how much insulin your body produces. This test can be a better way to measure insulin levels as C-peptide tends to stay in body for longer time than insulin and inactive. Why Get Tested? To help evaluate insulin production by the beta cells in the pancreas or to help determine the cause of low blood glucose (hypoglycemia) hence differentiate between type I and Type II diabetes mellitus. Type- 1 has low level of C-peptide treated with insulin administration, while Type- 2 has high level of C- peptide treated with hypoglycemic drugs. 8