AIM STEP 10
4th Year MBBS
Endocrine + Reproduction
4th Year MBBS
Endocrine + Reproduction
Student Memory Support
Diabetes Mellitus: Pathogenesis, Diagnosis, Chronic Management and Population Prevention
High-yield memory reinforcement for rapid KMU-focused revision. :contentReference[oaicite:0]{index=0}
1. High-Yield Flashcards
Tap each question to reveal the answer.
What are the two central abnormalities in type 2 diabetes mellitus?
Insulin resistance and progressive pancreatic β-cell dysfunction.
What is the principal mechanism of type 1 diabetes mellitus?
Autoimmune destruction of pancreatic β-cells causing severe or absolute insulin deficiency.
Why does polyuria occur in uncontrolled diabetes?
Glycosuria causes osmotic diuresis, increasing urinary water loss.
What fasting plasma glucose value meets a diagnostic criterion for diabetes?
Fasting plasma glucose ≥126 mg/dL (7.0 mmol/L).
What HbA1c value is consistent with diabetes when measured appropriately?
HbA1c ≥6.5%.
What is the key metabolic difference between DKA and HHS?
DKA has marked ketogenesis from severe insulin deficiency; HHS has enough residual insulin to limit major ketosis.
Which three major microvascular complications occur in diabetes?
Retinopathy, nephropathy and neuropathy.
How do sulfonylureas stimulate insulin secretion?
They close β-cell ATP-sensitive potassium channels, causing depolarization, calcium influx and insulin release.
What is the main glucose-lowering action of metformin?
It primarily reduces hepatic glucose production and also improves insulin sensitivity.
Which receptor is activated by pioglitazone?
PPAR-γ, a nuclear receptor that improves insulin sensitivity through altered gene transcription.
Why do α-glucosidase inhibitors cause flatulence?
Delayed carbohydrate digestion allows more carbohydrate to reach the colon for bacterial fermentation.
How does sitagliptin lower blood glucose?
DPP-4 inhibition prolongs endogenous incretin activity, increasing glucose-dependent insulin release and reducing glucagon.
What are the principal actions of pramlintide after a meal?
It slows gastric emptying, suppresses inappropriate postprandial glucagon and increases satiety.
Which clinical finding strongly suggests significant insulin resistance?
Acanthosis nigricans, especially with central obesity and hyperinsulinaemia.
What are the three levels of prevention applied to diabetes?
Primary prevention, secondary prevention and tertiary prevention.
Which insulin preparation can be given intravenously during acute diabetic ketoacidosis management?
Regular insulin.
2. Mnemonics
Mnemonic Title: Classic Hyperglycaemic Symptoms
3 Ps
Meaning: Polyuria → Polydipsia → plus the commonly linked polyphagic drive; remember that weight loss may still occur when insulin deficiency is marked.
Mnemonic Title: Diabetic Microvascular Complications
R-N-N
Meaning: Retinopathy → Nephropathy → Neuropathy.
Mnemonic Title: Levels of Diabetes Prevention
P-S-T
Meaning: Primary → prevent or delay disease; Secondary → screen and detect early; Tertiary → limit disability from established complications.
3. Memory Tables
Type 1 versus Type 2 Diabetes Mellitus
| Feature | Type 1 | Type 2 |
|---|---|---|
| Main defect | β-cell destruction | Insulin resistance + β-cell failure |
| Endogenous insulin | Markedly deficient | May be high early, then declines |
| Ketosis tendency | High | Lower in stable disease |
| Key treatment | Insulin required | Lifestyle + individualized drugs ± insulin |
Major Glucose-Lowering Drug Classes
| Drug / Class | Main Action | Memory Point |
|---|---|---|
| Sulfonylureas | ↑ Insulin secretion | Hypoglycaemia |
| Meglitinides | Short mealtime insulin release | Postprandial control |
| Metformin | ↓ Hepatic glucose production | Low hypoglycaemia risk alone |
| Pioglitazone | PPAR-γ activation | Oedema / heart failure caution |
| Acarbose | ↓ Carbohydrate digestion | Flatulence |
| Sitagliptin | DPP-4 inhibition | Glucose-dependent effect |
4. Rapid Revision Points — Last-Minute Revision
Must Remember:
- Type 1 diabetes results from β-cell destruction and requires insulin replacement.
- Type 2 diabetes combines insulin resistance with progressive β-cell dysfunction.
- A fasting plasma glucose of ≥126 mg/dL is diagnostic when appropriately confirmed.
- A 2-hour OGTT value of ≥200 mg/dL meets a diagnostic criterion for diabetes.
- DKA results from severe insulin deficiency with lipolysis, ketone formation and metabolic acidosis.
- Chronic hyperglycaemia causes microvascular injury and accelerates atherosclerosis.
- Sulfonylureas and meglitinides can cause hypoglycaemia because they stimulate insulin secretion.
- Metformin lowers hepatic glucose production and generally does not cause hypoglycaemia when used alone.
- Pioglitazone improves insulin sensitivity but fluid retention can worsen heart failure.
- Primary prevention reduces risk factors; secondary prevention detects disease early; tertiary prevention limits disability.
Common KMU Trap: Do not classify type 1 and type 2 diabetes by age alone. Mechanism, clinical pattern and evidence of endogenous insulin production are more informative.
5. Clinical Memory Hooks
Polyuria + polydipsia + weight loss
→
hyperglycaemia with osmotic diuresis; marked weight loss suggests significant insulin deficiency.
→
hyperglycaemia with osmotic diuresis; marked weight loss suggests significant insulin deficiency.
Central obesity + acanthosis nigricans
→
insulin resistance with compensatory hyperinsulinaemia.
→
insulin resistance with compensatory hyperinsulinaemia.
Vomiting + dehydration + deep rapid breathing in diabetes
→
suspect DKA from ketone-associated metabolic acidosis.
→
suspect DKA from ketone-associated metabolic acidosis.
Painless plantar ulcer + reduced sensation + weak pulses
→
diabetic neuropathy plus peripheral arterial disease causing impaired protection and healing.
→
diabetic neuropathy plus peripheral arterial disease causing impaired protection and healing.
6. Starred High-Yield Exam Points
- ⭐ Type 1 diabetes: autoimmune β-cell destruction → absolute insulin deficiency → insulin is essential.
- ⭐ DKA: insulin deficiency → lipolysis → ketone-body production → metabolic acidosis.
- ⭐ Diabetes diagnosis: fasting plasma glucose ≥126 mg/dL, 2-hour OGTT glucose ≥200 mg/dL or HbA1c ≥6.5% are established diagnostic routes.
- ⭐ Sulfonylureas close β-cell KATP channels; hypoglycaemia is the major adverse effect.
- ⭐ Metformin mainly decreases hepatic glucose production; gastrointestinal upset is common and lactic acidosis is a rare serious risk.
- ⭐ Pioglitazone activates PPAR-γ; fluid retention makes heart failure an important caution.
- ⭐ Screening detects asymptomatic disease and therefore represents secondary prevention.