Type 2 Diabetes Flashcards
What is diabetes?
- Inadequate secretion of insulin
- diorder of CHO metabolism caused by hereditary & environmental factors
- Poorly controlled blood glucose - hyperglycaemia
- Defective insulin secretion and/or utilisation - skeletal muscle/liver
- causes excessive urine production & elevated blood glucose levels
- Defective lipid metabolism
How is diabetes diagnosed?
- Diagnosed on a fasting plasma glucose measurement/an oral tolerance test(75g oral glucose consumed & plasma glucose concentrations monitored over 2 hrs)
- Recently diagnosed through HbA1c concentration as this shows the plasma glucose over the past 3 months
- Can be predicted by BMI & waist circumference(waist-to-hip ratio)
- regular exercise has been shown to reduce HbA1c levels, both alone and in conjunction with dietary intervention
How can diabetes impact different people?
9.3% of the world’s population 20-79 live with diabetes
- more prevalence in men than women
- Afro-Caribbean/African American ethnicity have twice the risk of diabetes than USA and UK
- People with the FTO gene leads to ~3kg higher body weight have increased risk of diabetes
- Not all obese people have diabetes, as able to store subcutaneous fat. visceral/ectopic fat = diabetes
Describe type 1 diabetes:
What is the risk of macrovascular complications elevated by?
Type 1(IDDM, insulin-dependent diabetes mellitus) - seen in childhood. Therefore need to inject insulin
- An autoimmune destruction of pancreatic β-cells, causing pancreas to be unable to produce insulin
- increased risk of both macrovascular disease in large blood vessels, CHD and stroke, kidney and nerves in hands & feet
- macrovascular complications are elevated by insulin resistance, evident in normoglycaemic insulin resistant individuals and in individuals with pre-diabetes
Describe type 2 diabetes:
Type 2(NIDDM, non-insulin-dependent diabetes mellitus) - initially related to obesity, quite high levels of insulin, doesn’t exert its action like it should to for glucose uptake into the liver
- Poor responsiveness of cells(muscle & adipose) to effects of insulin
- Mainly found in high income countries, due to highly sugared food access
- Hyperinsulinemia(high fasting insulin concentration) in the presence of normal/elevated blood glucose separated type 2 from type 1
How does insulin resistance affect the regulation of blood glucose?
- resistance of peripheral tissues (skeletal muscle) = less glucose is cleared from the blood for a given concentration of insulin.
- insulin resistance in the liver making insulin less effective at suppressing hepatic glucose production when this is metabolically appropriate e.g.: after a meal
What is the role of glucose in lipid metabolism?
- promote the uptake and storage of FA in adipose tissue, inhibit their mobilisation from adipose tissue & decrease secretion of VLDL from the liver.
- Without this plasma TG concentration increases
- also increase non-esterified fatty acids, which compromise tissues ability to clear glucose
What was the correlation seen between EE and risk of diabetes?
How was risk of T2DM correlated to sitting time?
- 1 increment in EE associated with 6% lower age-adjusted risk of developing diabetes
- risk of type 2 diabetes increased by 1% for every hour per day increase in total sitting
How can insulin impact the metabolism of lipids?
- Promotes storage & uptake of FFA in adipose tissue
- Increases hepatic VLDL secretion & decreases clearance of VLDL and chylomicrons from circulation, resulting in higher plasma triglyceride concentrations. Associated with CVD risk
- Causes elevated NEFAs which compromises tissues ability to clear glucose, furthering insulin resistance
- Research has suggested that patients with type 2 diabetes had smaller mitochondria, causing a lower capacity for skeletal muscle to oxidise fat. Leading to the accumulation of intramuscular lipid, impairing insulin signalling and causing insulin resistance
What are the main hormones for glucose regulation?
- How is blood glucose regulated?
How are the levels different in diabetics?
Main hormones for glucose regulation:
Glucagon
Insulin
GLP-1
GLP
* Glucagon produced by alpha cells in pancreas encourages liver to pump glucose into blood to keep glucose relatively normal
- Diabetics have high prolonged glucose due to insulin resistance in skeletal muscle
- Diabetes therapy is to prevent blood vessel diseases
What are the plasma glucose levels for diabetes diagnosis?
- Fasting:
normal = <6mmol/L
impaired = 6-6.9 mmol/L
diabetes = >7mmol/L - 120min after 75g glucose
normal = <7.8mmol/L
impaired = >7.8-11.1
diabetes = >11.1 - HbA1c:
normal = <6%
pre-diabetes = 6-6.4%
diabetes = 6.5%
How can type 2 diabetes impact the risk of premature mortality?
- 15% higher risk of death in type 2 diabetes patients
- each 1% increase in HbA1c leads to an increased 12% in mortality risk
Name some major complications due to diabetes:
Microvascular disease:
* retinopathy(leading cause of blindness)
* Nephropathy (cause of kidney disease)
* Neuropathy - somatic or autonomic nerve damage(diabetic foot, leading to amputation)
- Really high blood sugar can cause damage to blood vessels causing them to rupture = things getting into eye that shouldn’t
Macrovascular disease:
*stroke(2-4x increased chance)
* 8/10 diabetics die from CVD
Describe how insulin resistance works in diabetics:
Not able to extract glucose out of circulation
- Liver still throws out glucose
- Contributing to the pre-longed level of blood glucose
- When β-cells become exhausted type 2 diabetes becomes type 1 –> ectopic is toxic for b-cells causing them to give in
What is the relationship between sedentary time and T2DM?
- little increase in T2DM with increased sitting time
- Alot higher with TV sitting time as people more likely to eat sugared foods
