10.2 - Diabetes Mellitus Flashcards
define diabetes mellitus
Elevated blood glucose concentration (hyperglycaemia) which over time leads to damage of the small and large blood vessels, causing premature death from cardiovascular disease
Why is DM a major health concern
- huge chunk of NHS budget
- Common cause of kidney disease
- Common cause of early blindness
- Most common cause of lower limb amputation
- Often leads to cardiovascular disease
- Life expectancy decreased
- Environment, lifestyle and diet are main cause
pathophysiology of DM overview
- when eat, body breaks down food to glucose
- As glucose rises, sends signal to pancreas
- Pancreas releases insulin
- Insulin binds to insulin receptor on cell wall
- This allows glucose to pass into cell
- In the cell, most of the glucose is used for energy right away
Simply, why does blood glucose rise in DM (two mechanisms)
- inability to produce insulin due to beta cell failure (T1) or….
- Insulin production is adequate but insulin resistance causes a relative insulin deficiency (T2)
Type 1 DM is due to…
autoimmune beta cell destruction
* Beta cells secrete insulin
* Autoantibodies made are directed against beta cells
* This destroys the insulin producing cells
* Partly genetic predisposition - but don’t know whole cause
Type 2 DM is due to…
- Obesity – in particular central obesity
- Muscle and liver fat deposition
- Elevated circulating free fatty acids
- Physical inactivity + lifestyle
- Genetic influences
- Relative insulin deficiency – body can still produce some of its own insulin but cells are unable to utilise it
How does DM present in general
typical symptoms of hyperglycaemia
* Polyuria
* Polydipsia – excessive thirst
* Blurring of vision - accumulation of glucose and the osmotic effects of this on the eye
* Urogenital infections (eg thrush)
symtoms of inadequate energy utilisation (as cells aren’t using the glucose)
* Tiredness
* Weakness
* Lethargy
* Weight loss
The severity of these symptoms will depend on the rate of rise of blood glucose as well as the absolute levels of glucose achieved
diagnosis of DM
- Fasting glucose test
- Oral glucose tolerance test
- HbA1c
Need symptoms and 1 abnormal test, or 2 if asymptomatic. Need to take tests twice in order to confirm diagnosis
Presentation of T1 DM
- Rapid onset (usually weeks)
- Weight loss, polyuria and polydipsia
- Late presentation there may be vomiting due to ketoacidosis
- Patient is usually young, less than 30 y/o
- Elevated venous plasma glucose
- Presence of ketones (breakdown products of fats)
treatment of T1 DM
- Must always treat with exogenous insulin
- This cannot wait due to complete inability to produce insulin (will die without it)
- Given by injection subcutaneous insulin several times per day
- Pumps and sensors can be used
importance of ketones in T1 DM
- Ketones are a breakdown product of fat
- If lose insulin, unable to get enough energy from glucose
- Will go on to use fats for energy
- As fats are broken down, these produce fatty acids and glycerol
- The fatty acids go on to form ketones, which are acidic
- Ketone production is supressed in presence of starvation, so in the absence of insulin, ketone production is activated
- Presence of ketones is indication for immediate insulin therapy
ketoacidosis
- fats are broken down uncontrollably as body is not getting enough glucose
- fats broken down produce fatty acids and glycerol
- fatty acids go on to produce ketones
- ketones are acidic
- this most often occurs in T1 diabetics
- diagnose: high blood sugar, high ketone level and low blood pH
post bariatric surgery or very low calorie diets and T2 DM
- post bariatric surgery, patients had a normalisation of blood glucose level very soon after surgery, without any associated weight loss. Suggests there are more factors than just weight loss.
- Before start losing weight systemically, losing fat from the liver + pancreas → start normalising blood glucose concentration.
- Therefore T2 diabetes can be considered as a potential reversible metabolic disorder precipitated by chronic intraorgan fat.
Presentation of T2 DM
- May have polyuria, polydipsia and weight loss
- No urinary ketones
- Maybe asymptomatic – diagnosis made by routine screen
- Patient is usually older (most over 40)
- Increasingly seen in younger people
- 90% of patients are overweight or obese
How should T2 DM be managed
- Weight loss (if lose 10% of weight loss and diagnosed relatively recently, might be able to go into remission)
- Low calorie (800 calorie) diet - need specialist dietician and meal replacement. This works in the short term
- Lifestyle changes
- Non insulin therapies
- Insulin - however this promotes deposition of fat, so doesn’t help (anabolic hormone)
- Require patient education and ability to monitor results of therapy
- Look for other risk factors eg BP, lipids, smoking, exercise + diet
- Monitor for chronic conditions
