Lecture 89: Type 1 diabetes

What is diabetes mellitus?

A group of metabolic disorders characterized by chronic hyperglycaemia due to defects in insulin secretion, insulin action, or both

What comorbidities may diabetes lead to?

CVD, neuropathy, retinopathy, sexual dysfunction, mental health, nephropathy, diabetic foot etc

What are the 3 primary types of diabetes?

Type 1, Type 2, and Gestational Diabetes

What are some rare forms of diabetes?

Latent autoimmune diabetes in adults (LADA), maturity onset diabetes of the young (MODY), double diabetes, type 3c diabetes, steroid induced diabetes

What is latent autoimmune diabetes in adults (LADA)?

A slower-onset form of type 1 diabetes, typically diagnosed in adults aged 30-50 - "type 1.5"

What is maturity onset diabetes of the young (MODY)?

Genetic form of diabetes usually appears <25 and may not require insulin

Only 1 mutation so action is not rapid and often when diagnosed have slight β cell action

What is double diabetes?

When type 1 develops into both type 1 and type 2

What is type 3c diabetes?

Diabetes is secondary to another condition

e.g. cystic fibrosis, pancreatitis, pancreatic cancer

What is steroid induced diabetes?

Steroids impair carbohydrate metabolism and increase insulin resistance

What is the honeymoon period in type 1 diabetes and why is it important to counsel patients on it?

• After starting insulin, remaining β-cells temporarily increase insulin production

• This leads to ↓ insulin requirements or temporary discontinuation

• Can confuse patients as control seems to “improve” but explain this is temporary

What are the symptoms of T1DM?

Often comes on quickly

4Ts = toilet, thirsty, tired, thinner

Other: thrush, cuts/wounds taking longer to heal, blurred vision

What is the diagnostic criteria for diagnosing T1DM?

Diagnose if patient is hyperglycaemic plus one of:

• Ketosis - ketones >2 in urine or >3mmol/L in blood

• Rapid weight loss

• Age under 50

• BMI under 25

• Family history of autoimmune disease

Possibly C-peptide test

What is the C-peptide test and what does this show in T1DM?

Measures endogenous insulin production

In T1DM, C-peptide levels are typically negative within five years due to autoimmune destruction of beta cells and can distinguish between T1DM and T2DM

What is diabetic ketoacidosis (DKA)?

A severe acute complication of diabetes, primarily seen in type 1 diabetes characterised by hyperglycaemia, ketonemia and acidosis

What are the common causes of DKA?

Infections, missed insulin doses, and new-onset diabetes

What are common causes of DKA?

Infections, missed insulin doses, and new-onset diabetes

What are the symptoms of DKA?

Excessive thirst, frequent urination, stomach pain, drowsiness, rapid weight loss, deep sighing breath, N/V

What is the pathophysiology of DKA?

• Total insulin deficiency

• ↑ Counter-regulatory hormones (glucagon, cortisol, adrenaline)

• ↑ Gluconeogenesis + glycogenolysis → hyperglycaemia

• ↑ Lipolysis → ketone production → metabolic acidosis

• Hyperglycaemia → osmotic diuresis → dehydration + electrolyte loss

What are the 6 factors of management of DKA management and how long are they treated for?

Fluids, insulin, potassium, electrolytes, resolution of DKA, restarting diabetes treatment

Treated typically over 24 hours

What is the main aims of administering fluids in DKA and how much should be administered?

Amount depends on estimated degree of dehydration

Main aims: restore circulatory volume, clear ketones, correct electrolyte imbalance

Why is insulin used in DKA?

Stops ketone production by eliminating the need for fat breakdown, reduces blood glucose and helps correct electrolytes

How is insulin given in DKA?

Fixed-rate IV insulin infusion based on body weight

Adjusted based on ketone clearance rates

What do you do during DKA if blood glucose normalises but ketones remain high?

Continue insulin to clear ketones

Add glucose infusion to prevent hypoglycaemia

Why is long-acting insulin used in DKA management?

Reduces infusion time

Avoids rebound hyperglycaemia when IV insulin is stopped

Prevents another DKA

Why are bicarbonate and phosphate levels low in the body during a DKA and how are these managed?

Bicarbonate: used in metabolic acidosis

Phosphate: lost in urine

Insulin and fluids normally correct

Why is K+ low in the body during DKA?

• In acidosis, H+ enters cell and K+ leaves into blood so level is normal/high

• Increased glucose in the blood so increased urination and K+ is lost in urine

What effect does insulin treatment have on potassium in DKA and why should this be carefully monitored?

• Insulin causes glucose and K+ to move into cells

• Blood K+ drops suddenly which can cause arrhythmias/cardiac arrest (monitor)

What are the values for the patient to be out of DKA?

pH >7.3

Bicarbonate >15mmol/L

Blood ketones <0.6mmol/L

What happens after DKA resolution in T1DM?

Convert to SC insulin after DKA is resolved and patient is ready to eat

What happens after DKA resolution in T2DM?

Decide between SC insulin or oral antidiabetics

How is insulin restarted after DKA?

Convert to SC glucose with meal, then stop IV 30-60 minutes later

If HbA1c acceptable → restart previous regimen

Do not restart at bedtime

How is a basal-bolus regimen restarted after DKA (when long-acting insulin sustained vs when long-acting is stopped during DKA?

Long-acting insulin should not have been stopped during DKA so just restart short-acting insulin with meals

If long-acting stopped, replace basal dose proportionally to IV and restart short-acting insulin with meals

How is a BD fixed-mix insulin regimen restarted after DKA?

Give SC insulin at usual time (with meal)

Stop IV 30–60 minutes later

How is an insulin pump restarted after DKA?

Recommence at usual basal rate

Continue IV insulin until meal short-acting bolus is given

What are the aims of providing SC insulin?

Match physiological requirements in both fasting and post-absorptive period, optimise any rise in blood glucose after a carbohydrate meal and avoid episodes of hyperglycaemia

What are the 5 different types of insulin (timing)?

Fast-acting, short-acting, intermediate-acting, long-acting, pre-mixed/biphasic

What is fast-acting insulin and give 3 examples (include when to take, how long it takes to start working and how long does it last)?

Usually taken before meals or as a correction dose, starts working in 5-10 minutes and lasts 2-5 hours

• NovoRapid, Fiasp, Humalog

What is short-acting insulin and give 1 example (include when to take, how long it takes to start working and how long does it last)?

Usually taken about 30 minutes before meals/just after eating, starts working in 30 minutes to 1 hour and lasts up to 8 hours (not often used)

• ActraRapid

What is intermediate-acting insulin and give 1 example (include when to take, how long it takes to start working and how long does it last)?

Usually taken once/twice a day, starts working within 2 hours and lasts 8-14 hours

• Humulin I

What is long-acting insulin and give 2 examples (include when to take, how long it takes to start working and how long does it last)?

Usually taken once/twice a day, starts working within 2 hours and lasts up to 18-24 hours

• Lantus, Tresiba

What is pre-mixed/biphasic insulin and give an example?

Gives basal insulin and short-acting insulin at once given 30 minutes before meal to cover carbohydrate contents

• NovoMix

Why must high-strength insulin not be withdrawn with a syringe?

Risk of dosing errors due to concentration differences → incorrect dose delivery

What are insulin biosimilars and give 2 examples?

Cost-effective alternatives to original insulins with similar safety profiles but not identical

• Abasaglar and Semglee

What must be considered when switching to a biosimilar insulin?

Careful dose adjustment and monitoring required

What are the most reliable sources for insulin administration history of a patient?

The patients themselves, their caregivers, or healthcare professionals like district nurses

What size needles are recommended for adults?

Usually 4mm but 8mm may require a lifted skin fold or inject into buttocks for proper injection

Where are the various sites for SC injections?

Abdomen and back of arms for faster absorption, or thighs and buttocks for slower absorption

How does aerobic and anaerobic exercise affect blood glucose in T1DM?

Aerobic → ↓ blood glucose → risk of hypoglycaemia
Anaerobic → ↑ blood glucose → risk of hyperglycaemia

What is insulin on board (IOB)?

Amount of active insulin in the body during exercise → affects glucose response

How is hypoglycaemia prevented during exercise?

If high IOB, this increases glucose uptake as well as exercise → consume small amounts of carbohydrates during exercise (“drizzle” carbs)

What is lipohypertrophy and what can it cause?

Local fat cells to enlarge and proliferate causing formation of dense tissue at the repeatedly injected site due to anabolic effects of insulin

Can cause unpredictable/delayed absorption

How should insulin be stored and how does this change before taking?

Store in fridge 2-8C but allow to come to room temperature before using

What are the sick day rules for T1DM?

• Never stop insulin

• Monitor blood glucose + ketones more frequently

• Maintain carbohydrate intake (even if unwell)

• Seek medical help if persistent hyperglycaemia/ketones or vomiting

How do you treat acute hypoglycaemia when you have T1DM?

Treat with anything that has 15-20g of carbohydrates like 200mL of orange juice, 60mL Glucojuice, 5 glucotabs, 6 dextrose tablets, 5 jelly babies

What is Glucagon used for and how does it work?

Used for severe hypoglycaemia when patient cannot take oral glucose (e.g. unconscious)

Stimulates liver glycogen breakdown → releases glucose into blood → raises blood glucose

What is included in family planning advice for Type 1 Diabetes Mellitus?

Folic acid 5 mg OD + refer to pre-natal/gestational diabetes clinic