Blood glucose levels and obesity

Blood Glucose level concentration Normal blood glucose levels are around 5 millimoles per litre (5mmol/l) The actual levels varies through the day depending on what the actual levels depends on the food we eat and out levels of activity, but the body try's to maintain a level around 5mmol/l. If a person is suffering from untreated diabetes their blood glucose levels may reach very high levels such as 30mmol/l.

Blood glucose levels and endothelial cells If blood glucose levels are the endothelial cell, which line body organs/blood vessels may absorb high levels of glucose. This process damages blood vessels and may lead to peripheral vascular disease, cardiovascular disease or stroke.

Microvascular disease (Eyes and Kidneys and limbs) Endothelial cells line small blood vessels as as arterials, and if blood glucose levels are high they absorb this excess glucose. This causes the basement membrane to become thick and weak. They may burst (haemorrage) and lack blood into the surrounding tissue. This can reduce the level of blood flow to other tissues or flood tissue with blood. Microvascular disease cause damage to the retina and the kidneys and may affect nerves cause peripheral nerve dysfunction.

Regulation of Blood glucose levels Negative Feedback Control Glucose is the principal energy sauce for most of the cells in the body. It is the “starting” molecule of respiration. As glucose only become available when a person has eaten food the body has to have a mechanism of storing and releasing glucose when needed. When blood glucose levels are high (after a meal) the body stores glucose as glycogen. When blood glucose levels are low (after fasting) the body releases the glucose from glycogen and raises blood glucose levels.

Glycogen Glycogen is made up on many molecules of glucose. When blood glucose levels are high the body makes glycogen Around 100g of glycogen is stored in the liver. Liver glycogen acts as a store of glucose.

Insulin and Glucagon Insulin Glucagon After a meal when blood glucose levels are high the pancreas detect the rise in blood glucose levels and produce the hormone insulin. Insulin is transported through the blood and picked up by insulin receptors on livers cells. The liver absorbs the excess glucose and converts it to glycogen. This lowers blood glucose levels After fasting blood glucose levels fall, this is detected by the pancreas and it releases the hormone glucagon. This is transported in the blood and activates a liver enzyme that converts the liver glycogen to glucose. This raises blood glucose levels

Homeostasis

Epinephrine (Adrenaline) During exercise or a flight or fight response the body needs to raise blood glucose level quickly. The adrenal glans secrete epinephrine into the blood. Epinephrine inhibits the action of insulin and promotes the breakdown of glycogen to glucose.

Diabetes is the inability to regulate blood glucose levels. If untreated blood glucose levels can rise to 30mmol/l and can cause damage to a wide variety of body cells and tissues.

Type of diabetes 5-10% of cases Early onset (Juvenile) Body weight is normal/underweight Pancreas can not produce insulin Cells have normal insulin sensitivity Requires injections of insulin 90-95% of cases Occurs in adulthood (late onset) Body weigh is normally overweight Pancreas can produce insulin Cells have fewer insulin receptor/less responsive to insulin Can be treated by diet, exercise and in some case insulin injections need

Glucose Tolerance Test This test examine the bodies ability to deal with ingested glucose. After fasting for 8 hours blood glucose levels are measured. They are then given a glucose solution of known concentration/volume (Glucose load) Blood glucose levels are then recorded for the next 2.5 hours and the results plotted on a graph. The results can then be analysed.

Glucose tolerance test (GTT)graph

Obesity and BMI Obesity is a condition characterized by the accumulation of excess body fat in relation to lean muscle. Being obese greatly increases an individuals risk of suffering a variety of health problems. One method use to determine obesity in the Body Mass Index (BMI) scale

Body Mass Index (BMI) There is an “ideal” range of body mass for each individual. A persons BMI is calculate by dividing a person mass in kg by their height in meters squared:- BMI= Body mass height2 BMI value Opinion of experts Risk of health problems 20-25 Ideal weight for height Average 26-30 Overweight Increased 31-40 Obese (Very overweight) Greatly increases +40 Very obese (Grossly overweight) Very greatly increased.

Limitations of BMI People with a high muscle mass, body builders have a high BMI and would be classified as obese.

Other methods for measuring body composition Densitometry A person mass in air and water is measured. As fat has a lower density than muscle a formula can be used to determine the body composition. Skin- fold thickness. Skin folds thickness are measures at various points on the body and again a formula is used to f=determine body composition. Bioelectric impedance. An electric current is passed through the body and the level of electrical resistance is used to estimate body fat levels. Waist to hip ratio. Used to determine if people are apples or pears. Apples type have a higher risk of developing CVD.

Causes of obesity Genetics, psychology, environmental metabolic and dietary factors all play a role in obesity. However the main contributor are excessive consumption of calories and lack of exercise.