Biology · Chemical Coordination and Integration · NEET
Diabetes mellitus happens when insulin is too low (or cells stop responding to it), so blood glucose stays high (hyperglycemia). This high glucose spills into the urine, called glycosuria, and because cells cannot use glucose properly, the body burns fat and makes ketone bodies that also appear in urine, called ketonuria. Memory hook: "Mellitus = honey urine" - sweet urine (glycosuria) plus acid ketones (ketonuria) are the two urine signs NEET always asks.
Low insulin raises blood glucose (hyperglycemia); the extra glucose spills into urine as glycosuria, while cells starved of glucose burn fat and release ketone bodies into urine as ketonuria - the two NEET urine signs of diabetes mellitus.
Your doubts, answered
What is the difference between diabetes mellitus and diabetes insipidus?
They sound alike but are totally different. Diabetes mellitus is a pancreas problem: insulin is low, so blood glucose is high and glucose leaks into urine (glycosuria). Diabetes insipidus is a pituitary problem: ADH (vasopressin) is low, so the kidney cannot save water and a lot of dilute urine is passed, but there is NO glucose in it. NEET loves to trap you here, so link mellitus to insulin/pancreas and insipidus to ADH/pituitary.
Why does glucose appear in the urine (glycosuria)?
Normally the kidney reabsorbs all the filtered glucose back into blood. In diabetes mellitus blood glucose is so high (prolonged hyperglycemia) that it goes above the kidney's reabsorption limit. The extra glucose that cannot be reabsorbed passes out with urine. That is glycosuria - glucose in urine.
What are ketone bodies and why do they form (ketonuria)?
Because insulin is missing, body cells cannot take in and use glucose for energy even though blood glucose is high. So the body breaks down fat instead. Burning fat fast produces acidic waste molecules called ketone bodies. When these spill into urine it is called ketonuria. Too many ketones make the blood acidic (ketoacidosis).
Which gland and hormone are responsible for diabetes mellitus?
The pancreas, specifically the beta cells of the islets of Langerhans, make insulin. When insulin secretion or action falls, diabetes mellitus develops. So the gland is the pancreas and the hormone is insulin, not the pituitary or ADH.
Is glycosuria or ketonuria the same as hyperglycemia?
No. Hyperglycemia means high glucose in the BLOOD. Glycosuria means glucose in the URINE, and ketonuria means ketone bodies in the URINE. Hyperglycemia is the cause; glycosuria and ketonuria are the two urine-analysis signs used to detect diabetes mellitus.
⚠️ The NEET trap ✗ Marking 'Hyperglycaemia' as a urine indicator of diabetes mellitus. ✓ The urine indicators are Glycosuria (glucose in urine) and Ketonuria (ketone bodies in urine). Hyperglycaemia is high blood glucose, not a urine finding. 🧠 NEET 2020 asked for URINE conditions. Hyperglycaemia is in the blood, so it cannot be the urine answer - the pair is Ketonuria + Glycosuria.
Real NEET questions
2020
Presence of which of the following conditions in urine are indicative of diabetes mellitus?
A · Ketonuria and Glycosuria ✓
B · Renal calculi and Hyperglycaemia
C · Uremia and ketonuria
D · Uremia and Renal Calculi
Solution: In diabetes mellitus, prolonged hyperglycemia pushes glucose into the urine (glycosuria), and because cells cannot use glucose, fat is broken down to make ketone bodies that also appear in urine (ketonuria). NCERT lists exactly these two as urine indicators. Hyperglycaemia is a blood finding, and renal calculi/uremia relate to other kidney disorders, so only 'Ketonuria and Glycosuria' is correct.
Solved Chemical Coordination and Integration NEET PYQs
Try the real previous-year questions from this chapter — each with the answer and a full solution.
