Why Diabetes Management Is Examined
Diabetes affects approximately 4.9 million people in the UK and is one of the most common long-term conditions managed in primary and secondary care. OSCEs examine it as a prescribing station (initiate or adjust diabetes medications), communication station (sick day rules, insulin counselling, driving regulations), and clinical reasoning (this patient's HbA1c is 85 mmol/mol, what do you do?). The landscape has changed significantly with SGLT-2 inhibitors and GLP-1 receptor agonists.
Type 1 vs Type 2 Diabetes, Distinguishing Features
| Feature | Type 1 | Type 2 |
|---|---|---|
| Mechanism | Autoimmune beta-cell destruction, absolute insulin deficiency | Insulin resistance + relative insulin deficiency |
| Onset | Typically under 30 years (but any age) | Typically over 40 years (but increasing in younger people) |
| Weight | Normal or thin | Usually overweight or obese |
| Onset of symptoms | Acute (weeks) | Insidious (years) |
| Ketosis | Prone to DKA | Resistant to ketosis |
| Treatment | Insulin always required | Lifestyle first; oral agents; insulin later |
| Autoantibodies | GAD, IA-2, islet cell antibodies | Absent |
| C-peptide | Low or undetectable | Normal or raised |
Type 2 Diabetes, NICE Step Therapy
Step 1: Lifestyle Modification
- Weight loss (even 5-10% of body weight improves glycaemic control)
- Mediterranean or low-carbohydrate diet
- 150 minutes/week moderate exercise
- Remission is achievable in early T2DM through significant weight loss (DiRECT trial: >15 kg loss produced remission in 86%)
Step 2: First-line Drug, Metformin
| Detail | Value |
|---|---|
| Mechanism | Reduces hepatic glucose output (primary); improves insulin sensitivity |
| Starting dose | 500 mg OD or BD with meals |
| Target dose | 1 g BD (standard; up to 2 g BD in some) |
| HbA1c reduction | 11-22 mmol/mol (1-2%) |
| Key contraindications | eGFR below 30 (stop); eGFR 30-44 (reduce dose, review); contrast investigations (pause), surgery (pause), acute illness with dehydration risk |
| Main side effects | GI (nausea, diarrhoea, take with food; use MR formulation); lactic acidosis (rare) |
| Weight effect | Neutral or slight reduction |
💡 Tip
Metformin is the only oral antidiabetic with proven cardiovascular mortality benefit (UKPDS). It should be continued throughout step therapy unless contraindicated.
Step 3: Second-line Agents (add to metformin)
| Drug class | Examples | Main indication | Key caution |
|---|---|---|---|
| SGLT-2 inhibitor | Empagliflozin, dapagliflozin, canagliflozin | CVD or CKD (proven cardio-renal protection) | eGFR below 45 (reduced efficacy); DKA risk; genital infections; sick day rules |
| GLP-1 receptor agonist | Semaglutide, dulaglutide, liraglutide | Obesity (significant weight loss) or CVD | Injectable (except oral semaglutide); pancreatitis risk |
| DPP-4 inhibitor | Sitagliptin, alogliptin | Tolerability; minimal side effects | Avoid with GLP-1 (same pathway) |
| Sulfonylurea | Gliclazide, glipizide | Low cost; add-on | Hypoglycaemia; weight gain |
| Pioglitazone | , | Resistant insulin resistance | Heart failure (contraindicated); fractures; bladder cancer |
🧠 Mnemonic
SGLT-2 inhibitors, key outcomes:
- S odium-glucose reduction (glycaemic)
- G lucose in urine (glycosuria), mechanism
- L eft ventricular benefits (heart failure hospitalisation reduced, EMPA-REG, DAPA-HF)
- T ype 2 DM + CKD, nephroprotection (CREDENCE, DAPA-CKD)
- 2 DKA risk, euglycaemic; stop when unwell/fasting/surgery
Type 1 Diabetes, Insulin Management
Insulin Types
| Type | Examples | Onset | Peak | Duration | Use |
|---|---|---|---|---|---|
| Rapid-acting analogue | Novorapid, Humalog, Apidra | 10-20 min | 1-2 hr | 3-5 hr | Mealtime bolus |
| Short-acting (soluble) | Actrapid, Humulin S | 30-60 min | 2-4 hr | 6-8 hr | IV infusion, pre-meal |
| Intermediate-acting | Insulatard, Humulin I | 1-2 hr | 4-12 hr | 18-24 hr | Background (basal) |
| Long-acting analogue | Lantus (glargine), Levemir (detemir) | 1-2 hr | Flat | 20-24 hr | Once daily basal |
| Ultra long-acting | Tresiba (degludec) | , | Flat | 42 hr | Once daily; more predictable |
Basal-bolus regime: long-acting insulin once daily + rapid-acting with each meal.
BD mixed regime: pre-mixed insulin (e.g., Novomix 30) twice daily, simpler but less flexible.
HbA1c Targets (NICE 2023)
| Patient group | HbA1c target |
|---|---|
| T2DM, lifestyle/metformin only | 48 mmol/mol (6.5%) |
| T2DM, drug with hypoglycaemia risk (sulfonylurea, insulin) | 53 mmol/mol (7.0%) |
| T1DM | 48 mmol/mol (6.5%) if no significant hypoglycaemia |
| Elderly/frail (individualised) | Up to 64 mmol/mol (8.0%), hypoglycaemia prevention prioritised |
Hypoglycaemia Management
Definition: blood glucose below 4.0 mmol/L
Symptoms: sweating, tremor, tachycardia (adrenergic); confusion, drowsiness, seizure (neuroglycopaenic)
Treatment, Rule of 15:
- If conscious and able to swallow: 15-20 g fast-acting carbohydrate (5 glucose tablets, 150 mL fruit juice, 3-4 glucogel sachets)
- Recheck in 15 minutes; repeat if still below 4.0
- Follow with long-acting carbohydrate (biscuit, piece of toast)
If unconscious or unable to swallow:
- IV glucose: 75-100 mL of 20% glucose (or 150-200 mL of 10% glucose), avoid 50% (vein-damaging)
- IM glucagon 1 mg, stimulates hepatic glycogenolysis (less effective if alcohol-related or depleted glycogen)
Sick Day Rules
⚠️ Red Flag
SICK DAY RULES for patients on insulin or SGLT-2 inhibitors:
- Never stop insulin during illness, even if not eating (continue basal; adjust bolus)
- Check blood glucose every 1-4 hours during illness
- Check blood ketones (type 1 diabetics), if above 0.6 seek advice; above 3.0 = seek emergency care
- Maintain fluid intake; eat easily digestible carbohydrates
- SGLT-2 inhibitors: STOP when acutely unwell, fasting, or awaiting surgery (DKA risk)
- Seek urgent medical review if: unable to keep fluids down, ketones raised, glucose not improving
Frequently Asked Questions
"What is the difference between type 1 and LADA (Latent Autoimmune Diabetes of Adults)?"
LADA is sometimes called type 1.5 diabetes. It is an autoimmune diabetes presenting in adulthood (typically 30-50 years), often initially misdiagnosed as T2DM. It progresses more slowly than classic T1DM, patients may not require insulin for months to years after diagnosis. Clues: non-obese adult, fails to respond adequately to oral agents, positive GAD antibodies, low C-peptide. Requires eventual insulin therapy. Important to identify because SGLT-2 inhibitors and sulfonylureas can precipitate DKA in LADA.
"What is the rationale for using an SGLT-2 inhibitor in a patient with T2DM and heart failure?"
SGLT-2 inhibitors reduce heart failure hospitalisation and cardiovascular mortality independently of their glycaemic effect, by mechanisms including natriuresis (osmotic diuresis), reducing cardiac preload and afterload, metabolic shift towards ketone utilisation, and direct cardiac and renal tubular effects. The EMPA-REG OUTCOME, CANVAS, and DECLARE trials demonstrated this in patients with T2DM. DAPA-HF and EMPEROR-Reduced extended this benefit to patients with HFrEF regardless of diabetes status. NICE now recommends SGLT-2 inhibitors in T2DM with CVD, CKD (eGFR above 45), or heart failure.
"What are the driving regulations for patients with insulin-treated diabetes?"
Group 1 licence (car/motorcycle): must inform DVLA; can drive if able to recognise hypoglycaemia, has had no severe hypoglycaemic episodes in the past 12 months, and monitors blood glucose as required (before driving and every 2 hours on long journeys). Do not drive if blood glucose below 5 mmol/L, treat and wait 45 minutes before driving. Group 2 licence (HGV/bus): much stricter, previously disqualifying, but DVLA now assess individually; regular HbA1c and hypoglycaemia records required.
"What is dawn phenomenon and Somogyi effect?"
Dawn phenomenon: physiological rise in blood glucose in the early morning (3-8 am) driven by circadian cortisol, growth hormone, and glucagon surges, seen in both T1DM and T2DM. Management: increase basal insulin dose or use ultra-long-acting insulin. Somogyi effect (rebound hyperglycaemia): nocturnal hypoglycaemia triggers counter-regulatory hormone release, causing rebound morning hyperglycaemia. Less common than once thought. Differentiate by continuous glucose monitoring, nocturnal hypoglycaemia precedes morning rise in Somogyi.
"When should insulin be initiated in type 2 diabetes?"
NICE recommends considering insulin when HbA1c remains above target (typically above 58 mmol/mol) despite optimised oral therapy, or when there are significant symptoms of hyperglycaemia. Start with a single daily dose of long-acting insulin added to existing oral therapy (basal-oral regime). Structured education, glucose monitoring, and hypoglycaemia training are essential before starting insulin. In some patients with very high HbA1c at presentation, a short course of insulin may be needed acutely, with deintensification later once control is achieved.
Related Posts
- Diabetes History OSCE, systematic history for the patient with known or suspected diabetes
- DKA Management OSCE, managing diabetic ketoacidosis as an acute complication
- Diabetic Foot Examination OSCE, examining for neuropathy, vascular disease, and foot complications