Diabetes: Basics ✅

Related Subjects: |Diabetes Mellitus: Basics |Type 1 Diabetes Mellitus | Type 2 Diabetes Mellitus | Type 3c Diabetes Mellitus |Gestational Diabetes |HbA1c |Hyperglycaemic Hyperosmolar State (HHS) |Diabetic Nephropathy |Diabetic Retinopathy |Diabetic Neuropathy |Diabetic Amyotrophy |Maturity Onset Diabetes of the Young (MODY) |Diabetes: Complications |Hypoglycaemia |Diabetic Ketoacidosis (DKA) Adults |Alcoholic Ketoacidosis |Euglycaemic Ketoacidosis (euDKA) with SGLT2 Inhibitors |Causes of Ketoacidosis

🩸🍬 Diabetes mellitus is a group of conditions where blood glucose is persistently too high. This happens because the body either makes too little insulin, cannot use insulin properly, or both. Long-term hyperglycaemia damages blood vessels, nerves, kidneys, eyes, feet and the heart.

📖 What is Diabetes?

• 🍞 Glucose is an important fuel for the body.
• 🔑 Insulin is a hormone made by pancreatic β-cells.
• 🚪 Insulin helps glucose move from the blood into body cells.
• ⬆️ If insulin is absent or ineffective, glucose stays in the blood → hyperglycaemia.
• 🩸 Chronic hyperglycaemia causes both microvascular and macrovascular complications.

🧬 Main Types of Diabetes

• 💉 Type 1 diabetes: Autoimmune β-cell destruction → absolute insulin deficiency.
• 🍎 Type 2 diabetes: Insulin resistance plus progressive β-cell dysfunction.
• 🤰 Gestational diabetes: Diabetes first diagnosed during pregnancy.
• 🫀 Type 3c diabetes: Diabetes caused by pancreatic disease or pancreatic damage.
• 💊 Secondary diabetes: Diabetes caused by drugs, endocrine disease or genetic conditions.

💉 Type 1 Diabetes

• 🛡️ Usually autoimmune.
• 🚫 The pancreas produces little or no insulin.
• 👶 Often presents in children, teenagers or young adults, but can occur at any age.
• ⚡ Symptoms often develop quickly: polyuria, polydipsia, weight loss and fatigue.
• 💉 Patients require lifelong insulin.
• 🚨 Risk of diabetic ketoacidosis if insulin is missed or insufficient.

🍎 Type 2 Diabetes

• 📈 The commonest type of diabetes.
• 🔒 Usually caused by insulin resistance with gradual β-cell failure.
• ⚖️ Often associated with overweight, obesity, increasing age, family history and some ethnic backgrounds.
• 😶 May be asymptomatic for years.
• 🥗 Managed with lifestyle measures, oral medication, injectable therapies and sometimes insulin.
• 🫀 Risk of cardiovascular, renal, eye, nerve and foot complications if not well controlled.

🤰 Gestational Diabetes

• 🤰 Diabetes first recognised during pregnancy.
• 🌸 Placental hormones increase insulin resistance, especially in the 2nd and 3rd trimester.
• 🧪 NICE diagnosis uses a 75 g oral glucose tolerance test.
• 📊 Diagnostic thresholds: fasting glucose ≥5.6 mmol/L or 2-hour glucose ≥7.8 mmol/L.
• 👶 Good glycaemic control reduces maternal and fetal complications.
• ⏳ Usually improves after delivery, but future type 2 diabetes risk is increased.
• 🥗 Management includes diet, glucose monitoring, metformin or insulin if needed.

🫀 Type 3c Diabetes

• 🫀 Also called pancreatogenic diabetes.
• 🔧 Caused by damage to the pancreas.
• 🔥 Causes include chronic pancreatitis, pancreatic cancer, cystic fibrosis, haemochromatosis or pancreatic surgery.
• 🍽️ Patients may have both insulin deficiency and pancreatic enzyme deficiency.
• ⚠️ Can be mistaken for type 2 diabetes.
• 💉 May need insulin.
• 💊 May need pancreatic enzyme replacement therapy if malabsorption or steatorrhoea is present.

💊 Secondary Diabetes

• 💊 Some diabetes is caused by another medical problem or medication.
• Drug causes: Corticosteroids, some antipsychotics, immunosuppressants and some cancer treatments.
• Endocrine causes: Cushing’s syndrome, acromegaly, phaeochromocytoma and hyperthyroidism.
• Genetic causes: MODY and neonatal diabetes.

🔍 Key Differences

🩺 Common Symptoms of Diabetes

• 🚽 Polyuria - passing urine frequently.
• 🥤 Polydipsia - excessive thirst.
• ⚖️ Unexplained weight loss.
• 😴 Tiredness and fatigue.
• 👁️ Blurred vision.
• 🦠 Recurrent infections, such as thrush or skin infections.
• 🩹 Slow wound healing.

🧪 Diagnosis

• 🧪 Diabetes can be diagnosed using HbA1c, fasting plasma glucose, random plasma glucose with symptoms, or an oral glucose tolerance test.
• 📊 HbA1c ≥48 mmol/mol, equivalent to 6.5%, supports a diagnosis of diabetes in many non-pregnant adults.
• 🍬 Random plasma glucose ≥11.1 mmol/L with symptoms supports diabetes.
• 🌅 Fasting plasma glucose ≥7.0 mmol/L supports diabetes.
• 🤰 In pregnancy, NICE uses specific OGTT thresholds for gestational diabetes.
• 🚨 Check ketones urgently if type 1 diabetes or DKA is suspected.

⚠️ Complications

• 🚨 Acute: Hypoglycaemia, diabetic ketoacidosis and hyperosmolar hyperglycaemic state.
• 👁️ Eyes: Diabetic retinopathy.
• 🫘 Kidneys: Diabetic kidney disease.
• 🧠 Nerves: Peripheral neuropathy and autonomic neuropathy.
• 🦶 Feet: Ulcers, infection and amputation risk.
• 🫀 Cardiovascular: Myocardial infarction, stroke and peripheral arterial disease.

🛠️ General Management Principles

• 🔍 Identify the correct type of diabetes.
• 🎯 Agree individualised glucose and HbA1c targets.
• 🥗 Support healthy eating, physical activity and weight management where appropriate.
• 💊 Use medication based on diabetes type, comorbidities and patient preference.
• 👁️ Screen for eye, kidney, nerve, foot and cardiovascular complications.
• 🧠 Educate patients on hypoglycaemia, sick-day rules and when to seek urgent help.

🚩 Red Flags

• 🤢 Vomiting, abdominal pain or drowsiness with high glucose or ketones.
• ⚖️ Rapid weight loss with thirst and polyuria.
• 🚨 New diabetes with ketones.
• 🤰 Pregnancy with hyperglycaemia or ketones.
• 🦶 Foot ulcer, spreading cellulitis or systemic infection.
• 🟡 New diabetes with jaundice, persistent abdominal pain or unexplained weight loss - consider pancreatic cancer.

🧠 Exam Pearls

• 💡 Type 1 diabetes = autoimmune β-cell destruction and absolute insulin deficiency.
• 💡 Type 2 diabetes = insulin resistance plus progressive β-cell dysfunction.
• 💡 Gestational diabetes = pregnancy-related insulin resistance.
• 💡 Type 3c diabetes = pancreatic damage causing diabetes.
• 💡 Do not assume all adult-onset diabetes is type 2.
• 💡 Ketones plus acidosis means DKA until proven otherwise.

📚 Summary

🩸 Diabetes mellitus is not one disease, but a group of conditions causing chronic hyperglycaemia. The key difference is the underlying mechanism: type 1 is insulin deficiency, type 2 is insulin resistance, gestational diabetes is pregnancy-related insulin resistance, and type 3c is caused by pancreatic damage. Correct classification matters because treatment, complication risk and patient education differ.