General Medicine
Diabetes Mellitus
Diabetes mellitus for MBBS: diagnostic thresholds, complications, drug therapy and the acute emergencies of ketoacidosis and the hyperosmolar state, mapped to NMC codes IM11.1 to IM11.24.
MedNext Academy | 3 min read
Diabetes Mellitus
Diabetes mellitus for MBBS: diagnostic thresholds, complications, drug therapy and the acute emergencies of ketoacidosis and the hyperosmolar state, mapped to NMC codes IM11.1 to IM11.24.
This chapter covers the classification, diagnosis and management of diabetes mellitus, including its microvascular and macrovascular complications. It gives particular attention to the acute emergencies of ketoacidosis, the hyperosmolar state and hypoglycaemia, and to the modern drug classes with cardiorenal benefit.
High-yield: Diabetes Mellitus
- Diabetes is diagnosed by a fasting glucose of 126 milligrams per decilitre or more, a two-hour value of 200 or more, or an HbA1c of 6.5% or more.
- A random glucose of 200 milligrams per decilitre or more with classic symptoms also confirms diabetes.
- Type 1 diabetes is autoimmune beta-cell destruction causing absolute insulin deficiency, usually in younger patients.
- Type 2 diabetes combines insulin resistance with progressive beta-cell failure and is strongly linked to obesity.
- Complications are divided into microvascular (retinopathy, nephropathy, neuropathy) and macrovascular (coronary, cerebrovascular, peripheral).
- Metformin is the first-line drug in type 2 diabetes unless contraindicated.
- SGLT2 inhibitors and GLP-1 receptor agonists offer cardiovascular and renal protection beyond glucose lowering.
- HbA1c reflects the average glucose over roughly the previous three months and guides long-term control.
- Diabetic ketoacidosis presents with hyperglycaemia, ketosis and a high anion gap metabolic acidosis.
- Ketoacidosis is managed with fluids, insulin and careful potassium replacement, correcting the potassium before insulin if it is low.
- The hyperosmolar hyperglycaemic state features very high glucose and osmolality with minimal ketosis.
- Hypoglycaemia is treated with fast-acting oral glucose if conscious or intravenous dextrose or glucagon if not.
- Annual screening for retinopathy, nephropathy and foot disease detects complications early.
- Blood pressure and lipid control are as important as glucose control in reducing cardiovascular risk.
- Structured education and self-monitoring improve glycaemic control and reduce complications.
Diabetes at a glance
- **Diagnosis:** Fasting 126, two-hour 200, HbA1c 6.5% or a random 200 with symptoms, all in milligrams per decilitre where relevant.
- **First-line drug:** Metformin, with SGLT2 inhibitors and GLP-1 agonists for cardiorenal protection.
- **Emergencies:** Ketoacidosis (ketosis, high anion gap) and hyperosmolar state (very high glucose, minimal ketosis).
- **Complications:** Microvascular (eye, kidney, nerve) and macrovascular (heart, brain, limbs).
NMC competencies in this chapter
- **IM11.1:** Definition and classification of diabetes mellitus
- **IM11.5:** Microvascular and macrovascular complications
- **IM11.11:** Laboratory tests for diagnosis and complications
- **IM11.16:** Pharmacologic therapies for diabetes
- **IM11.18:** Drugs for target-organ protection in type 2 diabetes
- **IM11.22:** Causes and initial treatment of hypoglycaemia
- **IM11.23:** Diabetic ketoacidosis
- **IM11.24:** Hyperosmolar hyperglycaemic state
Frequently Asked Questions
What are the diagnostic thresholds for diabetes?
Diabetes is diagnosed by a fasting plasma glucose of 126 milligrams per decilitre or more, a two-hour value of 200 or more, an HbA1c of 6.5% or more, or a random value of 200 with classic symptoms.
How is diabetic ketoacidosis managed?
It is treated with intravenous fluids, insulin and careful potassium replacement, with potassium corrected before insulin if it is low, while the precipitant is identified and treated.
Which drugs give cardiorenal protection in type 2 diabetes?
SGLT2 inhibitors and GLP-1 receptor agonists provide cardiovascular and renal benefits beyond their glucose-lowering effect, and are chosen in patients with such risk.
How does this chapter help for NEET-PG?
The diagnostic thresholds, ketoacidosis management, complication categories and modern drug classes are frequently tested and map directly to exam questions.
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