Drugs to treat Diabetes Flashcards
What is the normal range of blood glucose before a meal?
4-6mmol/L
What is the normal range of blood glucose after a meal?
7-8mmol/L
What is hypoglycaemia ?
this is when the blood glucose is below normal <4mmol/L
What are the consequences of hypoglycaemia ?
confusion and loss of consciousness; as the brain cells are starved of glucose
hypoglycaemia coma and possible death if not treated promptly
What is the treatment for hypoglycaemia ?
to administer glucose
What is hyperglycaemia?
this is when blood glucose levels are above normal
fasting levels >7mmol/L
random levels >11mmol/L
What are the consequences of hyperglycaemia
damage to endothelial cells lining the lumen of the blood vessels
microvascular complications- damage to capillaries in retina (retinopathy), kidneys (nephropathy)
macrovascular complications: poor peripheral circulation leading to tissue damamge (heart attack, stroke)
peripheral nerve damage (peripheral neuropathy)
damage to insulin producing cells in the pancreas
diabetic ketoacidosis
hyperglycaemic coma
What is ketoacidosis?
this is a metabolic state that is associated with pathologically high levels of serum and urine concentrations of ketones.
Occurs in hyperglycaemia and insulin deficiency which causes unopposed lipolysis and the oxidation of free fatty acids thus resulting in ketone production
What us diabetes mellitus?
this is a condition where the body cannot regulate the use of glucose properly so blood glucose levels become too high
Diabetes mellitus is the 9th leading cause of death with 1.5 million deaths caused by DM. True or false
True
The NHS spends what percentage of its budget on treating DM and its complications?
10%
What are the causes of diabetes mellitus ?
genetics
gender
relocation
lifestyle- diet, exercise
When was the earliest known record of diabetes made? What was reported?
1552 BC by a physician Hesy- Ra who reported/mentioned frequent urination
When was diabetes first named? What are the origins?
Greek Physician Aretaeus of cappadocia named the condition diabetes in 100 AD
Diabetes is greek for siphon; came about since people with diabetes urinated so often
How was diabetes originally diagnosed in the 1100s AD?
urine of those with diabetes thought to be sweet tasting
Water tasters drank urine of those thought to have diabetes
When was mellitus added to diabetes? What are the origins of mellitus ?
1700s AD by an edinburgh trained surgeon John Rollo
comes from Latin and Greek words meaning honey
When were important discoveries made regarding better understanding and treatment of diabetes mellitus?
1800’s and onwards
What are the two types of cells in the pancreas?
exocrine cells (secrete pancreatic fluids containing digestive enzymes)
endocrine cells
What are the islet of langerhans?
regions of the pancreas that contains endocrine cells discovered by a German medical student Paul Langerhans
Help produce the hormone insulin
The islet of langerhans make up __% of the pancreas
4.5%
What cells in the pancreas are responsible for the production of digestive enzymes?
acinar cells
What is a hormone?
a chemical messenger produced by a particular gland or cells of the endocrine system
What is endocrine signalling?
this is when signalling molecules from the signalling cel travel through the bloodstream to the target cell
What is paracrine signalling?
this is when the signalling and target cell are close together
What is autocrine signalling?
this is when the signalling and target cell are the same cell
Glucagon is produced by …
alpha cells of the pancreas
What is the effect of glucagon on blood glucose?
raises blood glucose levels
causes the liver to convert stored glycogen into glucose which is released into the blood stream
Insulin is produced by which cells?
beta cells
What is the effect of insulin on blood glucose?
lowers blood glucose levels
cells in the liver, muscle and fat tissue take up glucose from the blood, storing it as glycogen in the liver and the muscle
The islet of langerhans contain four type of cells. List them and what they produce
Alpha cells- glucagon
Beta cells- insulin
Delta cells - somatostatin
P(F) cells- pancreatic polypeptide
What hormone is released by the pancreas in hypoglycaemia ?
glucagon
(raise blood glucose levels)
What hormone is released by the pancreas in hyperglycaemia?
Insulin
to lower blood glucose levels
What is the effect of glucagon on hepatocytes?
glucagon binds to receptors on hepatocytes and causes glucose channels to open
this then switches on enzymes that breakdown glycogen into glucose
this allows glucose to flow through the cell membrane out of the cell (via the glucose channels)
What is glycogenolysis?
breakdown of glycogen into glucose
Describe on a molecular level what occurs in order to resolve hyperglycaemia in liver cells
(liver/muscle/fat cells)
Insulin is released by beta cell in the islet of langerhans in response to high blood glucose
insulin binds to receptors on hepatocytes
this causes glucose transporters (GLUT2) to open
this allows glucose to flow though the cell membrane into the cell
insulin binding also switches on enzymes that convert glucose to glycogen
What is gluconeogenesis?
It is a pathway by which non-hexose precursors such as glycerol, lactate, pyruvate and glucogenic amino acids are converted into glucose for storage
What is the main glucose transporters expressed in hepatocytes?
GLUT2
What is the main glucose transporter expressed in striated muscle?
GLUT4
Describe on a molecular level what occurs in order to resolve hyperglycaemia in striated muscle cells
insulin binds to receptors on the striated muscle cells
this opens glucose transporters (GLUT4)
this allows glucose to flow through the cell membrane into the cell
insulin binding also switches on enzymes that converts glucose to glycogen
Describe on a molecular level what occurs in order to resolve hyperglycaemia in adipocytes
insulin binds to receptors on the adipocytes
this opens GLUT4 transporters
this allows glucose to flow through the cell membrane into the cell
glucose undergoes a number of actions to form glycerol
one glycerol molecule binds to 3 fatty acid molecules to form a triglyceride
As opposed to glycogen, what transformation to glucose is performed in adipocytes?
glucose forms glycerol
What is insulin resistance?
this is a pathological condition in which cells fail to respond normally to the hormone insulin
What does a disruption in the insulin signalling pathway in hepatocytes, skeletal muscle cells and adipocytes lead to ?
prevent the uptake of glucose into these cells
resulting in elevated blood glucose levels
Leads to type 2 diabetes
Briefly describe how glucose sensing leads to insulin release in beta cells
glucose enters beta cells via GLUT2 glucose transporters
glucose is metabolised by GCK (glucokinase)
metabolism of glucose causes an increase in ATP:ADP ratio
increase in ATP:ADP ratio is detected by Katp channels (potassium channels)
The K+ channels close (preventing loss of K+ ions) which leads to depolarisation of the cell- as it becomes more positive
depolarisation to opening of voltage gated calcium ion channels which allow calcium ions diffuse into the cell
Ca2+ induced exocytosis of insulin occurs
Aside from glucose, what other molecules can cause the pancreatic beta cell to release insulin?
amino acids
hormones
neurotransmitters
Briefly describe a mechanism outside of glucose sensing by which beta cells release insulin
Incretins such as GLP1 (glucagon like peptide) are hormones released from intestinal endocrine cells
they travel in the blood (as per endocrine signalling) and bind to receptors on beta cells which result in intracellular signalling
Intracellular signalling causes released of calcium ions from intracellular stores
Calcium induced exocytosis of insulin occurs
How are drugs designed to treat type 2 diabetes?
the drugs can target the disrupted pathways to try and correct insulin release
What are the other names of type I diabetes?
insulin dependent diabetes mellitus
juvenile diabetes
When does T1DM develop?
usually before the age of 20
with a peak at 12 years old
What is the cause of T1DM?
autoimmune destruction of pancreatic beta cells
insufficient or non existent production of insulin