Matthew (Diagnosis and treatment of T1DM) Flashcards
What is type 1 diabetes?
When the pancreas no longer produces insulin.
Which cells in the pancreas are responsible for producing insulin?
Beta cells
What are the 3 functions of insulin?
1- Reduces blood glucose levels
2- Promotes body growth and development
3- Ensures we have adequate energy stores
Facilitates glucose uptake and utilisation in cells and tissues.
Stimulates breakdown of glucose and storage in the liver as glycogen serving as ‘energy’ storage
Signs and symptoms of T1DM
- Excessive thirst
- Excessive urination
- Recurrent UTI
- Sweet smelling urine
- Superficial infections (ringworm or thrush)
- Weight loss
- Blurred vision
- Confusion
- Vomiting
- Drowsiness
- Slow healing wounds
Renal glucose reabsorption
Body wants to keep as much glucose as possible as it is our main energy source so it will be reabsorbed in the PCT.
There is a threshold to how much can be reabsorbed so one this is reached glucose will go out in the urine.
Because glucose has a high osmolarity it pulls water out with it which leads to dehydration (why T1DM have symptoms of excessive urination and thirst). This creates a state of hyper filtration- kidney is in overdrive.
When you start to treat the diabetes it can cause issues with kidney function- change creatinine clearance which can cause problems in the elderly
What is diagnosis based on?
- Clinical presentation and symptoms
- Family history - history of autoimmune diseases (Addisons, rheumatoid arthritis, hyperthyroidism, coeliac). In patients that have a strong family history of T1DM you can consider that there might be a genetic influence and that it is actually monogenic diabetes instead of type 1.
- Capillary blood glucose - expect to be high, can’t diagnose without. Important to know if it is fed or fasted- ideally want fasted glucose levels. Above 11 is classed as hyperglycaemia
- HbA!c- important for target setting
HbA1c
Measure blood glucose control over the past 3 months (because the lifespan of RBC is 90-120 days).
Not essential for diagnosis of T1DM as wouldn’t be raised in patients with classic acute onset as glucose won’t have had time to bind to Hb.
Still used in practice as is clinically useful to guide differential and monitoring.
Usually do test twice when diagnosing.
When diagnosis isn’t clear
- High BMI
- More advanced age (>50)
- Insidious onset of symptoms
Further investigations:
- Urinary C peptide
- diabetes specific antibodies
- Genetic testing (MODY - monogenic diabetes- mutations in only a single gene)
What are the main parts of a beta cell?
- Glutamate decarboxylase (GAD)
- Insulin
- Islet Antigen-2 (IA-2)
- Zinc transporter 8 (ZnT8)
- Insulin Granule
If you suspect type 1 then you should start treatment before waiting for autoantibody test results to come back as this can take a while.
Most commonly there will be a rise in GAD. The more positive antibodies they have the more likely they are to have type 1 diabetes.
Diabetes autoantibodies
Helpful if clinical picture is unclear or if needed for coding and access to health technologies which is a huge part of proper patient care.
- Evidence T1DM is an autoimmune condition is based on the presence of DAAs most specific to islet cell destruction (ICAs, GAD65/67Abs, IA-2Abs, or IAAs)
- Lack of these in a completely insulinopenic patient would suggest type 3c/type 1B (idiopathic)
- ICAs (Islet Cell Autoantibodies) were previously the main method to confirm T1DM but GAD, IAA, and IA-2 have been shown to be more precise and definitive predictive/diagnostic measures
Presentation/presence of autoantibodies doesn’t;t always follow specific pattern so not definitive at time of diagnosis. In the majority of patients GAD will be the first indicator.
C-peptide
- C-peptide is a by product of the breakdown of endogenous pro-insulin.
- The bodies natural precursor to insulin
- Made in equal amounts to insulin protein so marker for level of insulin productions
Not used routinely to monitor or test for type 1
- Requires endogenous insulin production
- Doesn’t account for ‘honeymoon’ period (when started on insulin some patients seem to ‘get better’ as the insulin that was given can kick the pancreas back into action. Usually stops after 12 months)
Most clinically useful to distinguish between forms of diabetes in those on insulin or to identify misdiagnosis 3-5 years into diagnosis or if unclear
- Benefit of which increase the further you are from point of diagnosis
Not useful early on in diagnosis.
Low C-peptide, high glucose = insulin deficient (type 1).
High C-peptide, high glucose = insulin resistance (type 2/MODY).
Often cheaper.
Faster to result as can e done at local labs rather than regional centres.
Goals of therapy
Glycaemic management- optimal insulin replacement with minimal episodes of hypoglycaemia
Prevention of microvascular and macrovascular complications
- Micro- retinopathy, neuropathy
- Macro- cardiovascular, peripheral vascular
Effectively managing cardiovascular risk factors
- Blood pressure, cholesterol, obesity
Providing approaches, treatments, and devices that minimise the psychosocial burden of living with type 1 diabetes and diabetes related distress while promoting psychological well-being.
- Can need a good understanding of maths and technology which can be hard for some people which leads to diabetes stress
Insulin formulation- Quick acting
Short acting (onset = 30-60 mins, duration = 6-8 hours)
- Actrapid
- Humulin S
- Hypurin Neutral
Rapid acting (onset = 10-20 mins, duration = 4 hours)
- Novorapid
- Humalog
- Apidra
- TruRapid
- Admelog
Very rapid acting (onset = 5-10 mins, duration = 3 hours)
- Fiasp
- Lyumjev
Insulin formulation- intermediate
Onset of action = 60-90 mins
Duration = 12-20 hours
- Humulin I
- Insulatard
- Hypurin isophane
Insulin formulation- biphasic
Analogue mix (onset = 10-20 mins, duration = 12-24 hours)
- Novomix
- Humalog Mix 25
- Humalog Mix 50
Isophane (onset = 30-60 mins, duration = 12-24 hours)
- Humulin M3
- Hypurin Mix 30/70
Insulin formulation- long acting
Long acting (onset = 2-4 hours, duration = 20-24 hours)
- Lantus
- Levemir
- Abasaglar
Ultra long acting (onset = 30-90 minutes, duration = 24-42 hours)
- Tresiba
- Toujeo
Insulin safety
Standards for safe insulin prescribing;
- Correct brand name
- Beware of sound alike
- Never prescribe by salt always by brand
- Correct device
- Never abbreviate ‘units’ to ‘u’ or ‘iu’ due to risk of 10x overdose
- Correct time
- Correct strength
- Write in full
Insulin is in the top 5 most dangerous drugs used worldwide and errors are very common. Some errors are minor e.g. dose is given 30 mins late. Some errors are almost fatal e.g. insulin pump removed, go into ketoacidosis, then suffer a cardiovascular event
