T1DM Flashcards
Features of DKA
abdominal pain
polyuria, polydipsia, dehydration
Kussmaul respiration (deep hyperventilation)
acetone-smelling breath (‘pear drops’ smell)
Use of HbA1c in diagnosis of T1DM
HbA1c is not as useful for patients with a possible or suspected diagnosis of T1DM as it may not accurately reflect a recent rapid rise in serum glucose
Which protein levels are typically low in patients with T1DM
C-peptide levels
Antibodies present in t1dm
Anti-GAD
Islet cell antibodies(ICA)
Insulin autoantibodies(IAA)
Diagnostic criteria for T1DM
If the patient is symptomatic:
fasting glucose greater than or equal to 7.0 mmol/l
random glucose greater than or equal to 11.1 mmol/l (or after 75g oral glucose tolerance test)
If the patient is asymptomatic the above criteria apply but must be demonstrated on two separate occasions.
How often should HbA1c be monitored in type 1 diabetics and what should their target be
should be monitored every 3-6 months
adults should have a target of HbA1c level of 48 mmol/mol (6.5%) or lower. NICE do however recommend taking into account factors such as the person’s daily activities, aspirations, likelihood of complications, comorbidities, occupation and history of hypoglycaemia
NICE advice on self-monitoring of blood glucose
recommend testing at least 4 times a day, including before each meal and before bed
more frequent monitoring is recommended if frequency of hypoglycaemic episodes increases; during periods of illness; before, during and after sport; when planning pregnancy, during pregnancy and while breastfeeding
Blood glucose targets in T1DM
5-7 mmol/l on waking and
4-7 mmol/l before meals at other times of the day
When do NICE recommend metformin in type 1 diabetes management
NICE recommend considering adding metformin if the BMI >= 25 kg/m²
Why is coeliac disease more common in those with T1DM
The HLA-DQ2 genotype sometimes seen in T1DM is also associated with coeliac disease, and therefore coeliac disease is more common in those with T1DM
What type of hypersensitivity reaction is involved in T1DM
T1DM is most commonly a type IV hypersensitivity autoimmune reaction, in which CD4+ T helper cells and CD8+ cytotoxic T cells attack pancreatic beta cells, eventually eliminating any insulin production
Why is there blurred vision in hyperglycaemia
Hyperglycaemia can cause an acute, reversible swelling of the lens.
This is a different mechanism to that seen in the chronic complication of diabetic retinopathy.
When is HbA1c unreliable
HbA1c can be unreliable if a patient has any concurrent condition affecting red blood cell survival.
What causes DKA
DKA is caused by uncontrolled lipolysis (not proteolysis) which results in an excess of free fatty acids that are ultimately converted to ketone bodies
Most common precipitating factors of DKA
The most common precipitating factors of DKA are infection, missed insulin doses and myocardial infarction.
Diagnosis of DKA
glucose > 11 mmol/l or known diabetes mellitus
pH < 7.3
bicarbonate < 15 mmol/l
ketones > 3 mmol/l or urine ketones ++ on dipstick
Mx of DKA
fluid replacement: most patients with DKA are deplete around 5-8 litres. Isotonic saline is used initially.
insulin: an intravenous infusion should be started at 0.1 unit/kg/hour. Once blood glucose is < 15 mmol/l an infusion of 5% dextrose should be started
correction of hypokalaemia
long-acting insulin should be continued, short-acting insulin should be stopped
Complications of DKA
gastric stasis
thromboembolism
arrhythmias secondary to hyperkalaemia/iatrogenic hypokalaemia
iatrogenic due to incorrect fluid therapy: cerebral oedema*, hypokalaemia, hypoglycaemia
acute respiratory distress syndrome
acute kidney injury
Pathophys of diabetic retinopathy
Hyperglycaemia is thought to cause increased retinal blood flow and abnormal metabolism in the retinal vessel walls. This precipitates damage to endothelial cells and pericytes
What does damage to endothelial cells and pericytes in the retinal vessel walls from hyperglycaemia result in
Endothelial dysfunction leads to increased vascular permeability which causes the characteristic exudates seen on fundoscopy.
Pericyte dysfunction predisposes to the formation of microaneurysms.
Neovasculization is thought to be caused by the production of growth factors in response to retinal ischaemia
Classification of diabetic retinopathy
Patients are typically classified into those with non-proliferative diabetic retinopathy (NPDR), proliferative retinopathy (PDR) and maculopathy.
Features of non-proliferative diabetic retinopathy
microaneurysms
blot haemorrhages
hard exudates
cotton wool spots (‘soft exudates’ - represent areas of retinal infarction), venous beading/looping and intraretinal microvascular abnormalities (IRMA) less severe than in severe NPDR
Key features of proliferative diabetic retinopathy
retinal neovascularisation - may lead to vitrous haemorrhage
fibrous tissue forming anterior to retinal disc
more common in Type I DM, 50% blind in 5 years
Key features of diabetic maculopathy
based on location rather than severity, anything is potentially serious
hard exudates and other ‘background’ changes on macula
check visual acuity
more common in Type II DM
General management of diabetic retinopathy
optimise glycaemic control, blood pressure and hyperlipidemia
regular review by ophthalmology
Management of diabetic maculopathy
if there is a change in visual acuity then intravitreal vascular endothelial growth factor (VEGF) inhibitors
Management of non-proliferative retinopathy
regular observation
if severe/very severe consider panretinal laser photocoagulation
Management of proliferative retinopathy
laser photocoagulation
intravitreal VEGF inhibitors
if severe or vitreous haemorrhage: vitreoretinal surgery
What causes diabetic foot disease
It occurs secondary to two main factors:
neuropathy: resulting in loss of protective sensation (e.g. not noticing a stone in the shoe), Charcot’s arthropathy, dry skin
peripheral arterial disease: diabetes is a risk factor for both macro and microvascular ischaemia
Presentation of diabetic foot disease
neuropathy: loss of sensation
ischaemia: absent foot pulses, reduced ankle-brachial pressure index (ABPI), intermittent claudication
complications: calluses, ulceration, Charcot’s arthropathy, cellulitis, osteomyelitis, gangrene
how should diabetics be screened for diabetic foot disease
All patients with diabetes should be screened for diabetic foot disease on at least an annual basis
screening for ischaemia: done by palpating for both the dorsalis pedis pulse and posterial tibial artery pulse
screening for neuropathy: a 10 g monofilament is used on various parts of the sole of the foot
DM sick day rules
Increase frequency of blood glucose monitoring to four hourly or more frequently
Encourage fluid intake aiming for at least 3 litres in 24hrs
If unable to take struggling to eat may need sugary drinks to maintain carbohydrate intake
It is useful to educate patients so that they have a box of ‘sick day supplies’ that they can access if they become unwell
Access to a mobile phone has been shown to reduce progression of ketosis to diabetic ketoacidosis
Diabetic nephropathy screening
all patients should be screened annually using urinary albumin:creatinine ratio (ACR)
should be an early morning specimen
ACR > 2.5 = microalbuminuria
BP control target if diabetic nephropathy
BP control: aim for < 130/80 mmHg
Management of diabetic nephropathy
dietary protein restriction
tight glycaemic control
benefits independent of blood pressure control have been demonstrated for ACE inhibitors (ACE-i) and angiotensin II receptor blockers (A2RB)
control dyslipidaemia(statins)
Use of C peptide test in diabetes
can be used to distinguish between type 1 and type 2 diabetes, as it can determine how much of their own insulin a person is producing, regardless of exogenous insulin
What is alopecia areata?
One or more round bald patches that appear suddenly, most often on the scalp - associated with diabetes
Risk factors for alopecia areata
FHx
FHx of autoimmune disease
Down syndrome
Drug induced(biologics)
Mx of alopecia areata
Treatment not always required because spontaneous regrowth common
Topical steroids
Minoxidil
Counselling
Camouflaging hair loss
