Carbohydrate intolerance and exercise (wk6) Flashcards
Regulation of blood glucose levels
-Glucose in the blood is essential to provide a constant flux of energy to the brain
-Exercise can significantly impact plasma glucose levels, as liver and muscle metabolism changes
-If the muscle needs more energy, this can be provided by the liver, as it can break down glycogen and is then released into the blood and the blood can take it up
-There are tight units for glucose and usually range from 4 to 7.8 mmol/L
-The muscle ATP demand can be met through liver glycogen and the glucose units in the body
-Glucagon drives the break down of liver glycogen
Describe the pancreas
-Insulin and glucagon
-Pancreatic islets (3 million; 2g tissue) are tiny clusters of pancreatic cells
-The pancreatic islets receive good oxygenated blood supply from major arteries, allowing rapid release of insulin and glucagon into the portal vein
-Insulin is secreted by the B (beta) – cells of pancreatic islets
-Glucagon is secreted by the A (alpha) - cells of pancreatic islets
-Insulin + glucagon are antagonistic hormones: insulin is secreted in response to elevated blood glucose, glucagon in response to low glucose. This allows the blood glucose levels to stay in the desired range in the body.
-Any insulin that is produced can be released rapidly, instantly. This means that the insulin released into the bloodstream can control blood glucose levels very quickly
-Before exercise if you have a high carbohydrate drink, the glucose will be used for energy. But if you’re resting, your body doesn’t need energy and the glycogen can therefore be stored to use in the appropriate manner later.
-Insulin stimulates the utilisation of biomolecules (glucose, FFA’s, amino acids) for storage or energy usage.
Describe glucose intolerance - Diabetes
-Includes clinical diabetes
-If you have glucose tolerance, then you have fasting glucose levels between 4 and 6 and are described as insulin sensitive.
-It means you can get dysregulation of glucose levels in the blood and can respond well through insulin released from the pancreas, but diabetics cannot and then can get a diagnosis
-Clinical diabetes means you may have a greater value of a fasting blood glucose level of 7.0 mmol/L and a random blood glucose test which would be greater than 10mmol/L. There is also a present level of glucose in urine. There would also be more than 10% of HbA1c. There would also be an impaired glucose clearance in an oral glucose tolerance test. The clinical symptoms would include: thirst, sweating and fatigue. There would be autoantibodies in the blood in type 1 diabetes. (If you have an autoantibody against the pancreas, it will recruit your own immune cells to the pancreas and destroy parts of the pancreas)
-There are also gene-environment interactions which contribute to the prognosis of diabetes in individuals, such as diet and exercise.
Describe type 1 and type 2 diabetes
-Type 1 diabetes -> In the immune system, certain types pf lymphocytes called T and B cells will attack the pancreas.
-Type 2 diabetes -> The health of the pancreas stays okay and healthy for a large amount of time. There is a loss of sensitivity to insulin.
-Short term complications of type 1 and 2 diabetes: thirst, sweating and hunger.
-Long term chronic effects include: diabetic retinopathy, diabetic nephropathy, stroke and CV diseases
Describe the benefits from exercise with type 1 and 2 diabetes (10)
-Preserved beta cell function
-Reduced autoimmunity
-Lower insulin requirements and improved insulin insensitivity
-Lower risk of blood lipid profile (LDL/HDL)
-Increased physical fitness and function
-Improved endothelial function (FMD)
-Reduced diabetic complications/lower modality rate
-Improved psychological well-being in children and adults
-Improved glycaemic control
Describe regular exercise improving glucose uptake
-Aerobic exercise increases GLUT4 expression in muscle, this is observed in the muscles that are most frequently used throughout 12 weeks of aerobic exercise training – type 1 fibres
-Exercise can improve insulin insensitivity, as assessed by routine clinical tests e.g., glucose tolerance test
-Single bouts of exercise impact (plasma glucose) -> Exercise can significantly impact plasma glucose levels in people with normal glucose control, but the response is dependent on the type of exercise:
* Increased – By glucose output – glycogenolysis/ gluconeogenesis in liver driven by epinephrine increases
* Decreased – By glucose uptake from working muscle – mediated by insulin
-Brief, maximal exercise can rapidly increase blood glucose as epinephrine stimulation to liver outweighs uptake my muscle (up to 10mmo.L-1)
-Prolonged exercise will lover plasma glucose levels as liver glycogen depots are depleted over time (as low as 2.5mmol.L-1)
Describe changed in blood glucose with exercise in T1D
-Resistance exercises -> 3 x 8 reps, 7 exercises, 90-s rest between sets (45min)
-Aerobic exercise -> 45 min on treadmill (60% of VO2 Max)
-No-exercise control -> 45 min of seated rest
-Regulation of blood glucose during exercise: 1TD ->
Hypoglycaemia during bouts of exercise
-Insulin-dependent diabetics must take caution when injecting insulin before exercise
-Insulin injectors before exercise may lead to a drop in blood glucose levels if not managed appropriately
-Fear of low blood glucose levels is a big barrier for exercise participation, particularly people with T1D
-For people with T1D, insulin injections are typically reduced (~50%) prior to undertaking exercise
-If someone who it taking insulin throughout the day starts to exercise everything is telling the body to remove glucose from the blood. Then as you exercise, the muscles tells your blood to take out more glucose so that the glucose level can be lowered. But because the diabetic cannot break down the glucose by the liver, the body ends up having low glucose levels.
