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