Oral glucose causes a much larger insulin response than intravenous glucose giving the same plasma glucose rise. This is mainly due to:

Incretin hormones such as GLP-1 from the gut

Somatostatin released from the stomach wall

Epinephrine released during digestion

Cortisol released in response to a meal

A 48-year-old man with acromegaly has a fasting plasma glucose of 7.6 mmol/L (137 mg/dL). Excess growth hormone raises his glucose mainly by:

Causing insulin resistance and more liver glucose output

Increasing glucose absorption from the intestine

Blocking insulin secretion by the beta cells

Causing autoimmune destruction of the beta cells

Glucose metabolism and regulating hormones

9 DOH Abu Dhabi (HAAD) lab licensing practice questions on Glucose metabolism and regulating hormones, part of Clinical Chemistry. The first 9 are below; the first 5 with answers and explanations (tap Show answer after you have chosen), the rest in Learn with a free account.

Question 1 · Easy
Insulin increases glucose uptake into skeletal muscle and fat cells by moving which transporter into the cell membrane?
1. AGLUT2
2. BGLUT4
3. CSGLT2
4. DGLUT1
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Answer: B · GLUT4
GLUT4 is stored in vesicles inside muscle and fat cells. When insulin binds its receptor, a tyrosine kinase, the vesicles move to the cell surface and glucose uptake rises within minutes. Poor GLUT4 movement in muscle is a central part of insulin resistance in type 2 diabetes. Exercise also moves GLUT4 to the membrane without insulin, which is one reason activity lowers glucose.
- A: GLUT2 is the high-capacity, insulin-independent transporter of the liver and intestine.
- C: SGLT2 reabsorbs filtered glucose in the proximal renal tubule.
- D: GLUT1 gives basal, insulin-independent uptake in red cells and the brain.
Question 2 · Medium
Oral glucose causes a much larger insulin response than intravenous glucose giving the same plasma glucose rise. This is mainly due to:
1. AIncretin hormones such as GLP-1 from the gut
2. BSomatostatin released from the stomach wall
3. CEpinephrine released during digestion
4. DCortisol released in response to a meal
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Answer: A · Incretin hormones such as GLP-1 from the gut
When nutrients reach the gut, L cells of the ileum and colon release GLP-1 and K cells of the duodenum release GIP. These incretins amplify glucose-dependent insulin secretion, so a large share of the insulin response to oral glucose comes from them. The incretin effect is reduced in type 2 diabetes. GLP-1 receptor agonists and DPP-4 inhibitors, which slow GLP-1 breakdown, are diabetes treatments based on this pathway.
- B: Somatostatin inhibits insulin secretion rather than boosting it.
- C: Epinephrine inhibits insulin release through alpha-adrenergic receptors.
- D: Cortisol does not acutely stimulate insulin secretion.
Question 3 · Easy
When plasma glucose starts to fall below normal, which two hormones act within minutes to raise it again?
1. ACortisol and growth hormone
2. BThyroxine and cortisol
3. CInsulin and somatostatin
4. DGlucagon and epinephrine
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Answer: D · Glucagon and epinephrine
The first defence against a falling glucose is a drop in insulin secretion, followed within minutes by glucagon and epinephrine. Both stimulate liver glycogen breakdown, and epinephrine also causes the warning symptoms of sweating, tremor and palpitations. Cortisol and growth hormone also raise glucose, but they act over hours by increasing gluconeogenesis and reducing glucose uptake. In long-standing type 1 diabetes the glucagon response is often lost, so these patients depend on epinephrine and are prone to severe hypoglycemia.
- A: Cortisol and growth hormone act over several hours, not minutes.
- B: Thyroxine and cortisol both act slowly and are not the first response.
- C: Insulin lowers glucose, and somatostatin damps islet hormone release.
Question 4 · Easy
Which adrenal hormone raises blood glucose over several hours and normally peaks in the early morning?
1. AAldosterone
2. BDHEA sulfate
3. CCortisol
4. DEpinephrine
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Answer: C · Cortisol
Cortisol follows ACTH secretion, with a peak around waking and its lowest level near midnight. It raises glucose by increasing liver gluconeogenesis and by reducing glucose uptake in muscle and fat. Its effect builds over hours, unlike the rapid action of epinephrine. Cushing syndrome and glucocorticoid treatment therefore often cause hyperglycemia.
- A: Aldosterone controls sodium and potassium balance, not glucose.
- B: DHEA sulfate is an adrenal androgen with little effect on glucose and little daily variation.
- D: Epinephrine comes from the adrenal medulla and acts within minutes.
Question 5 · Medium
A 48-year-old man with acromegaly has a fasting plasma glucose of 7.6 mmol/L (137 mg/dL). Excess growth hormone raises his glucose mainly by:
1. AIncreasing glucose absorption from the intestine
2. BBlocking insulin secretion by the beta cells
3. CCausing autoimmune destruction of the beta cells
4. DCausing insulin resistance and more liver glucose output
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Answer: D · Causing insulin resistance and more liver glucose output
Growth hormone is a counter-regulatory hormone. It reduces glucose uptake in muscle and fat, increases lipolysis, and the extra free fatty acids worsen insulin resistance, while liver glucose output rises. Insulin levels are usually high as the beta cells try to compensate, and diabetes appears when they can no longer keep up. Glucose tolerance often improves once the pituitary tumor is treated.
- A: Growth hormone does not meaningfully increase intestinal glucose absorption.
- B: Insulin levels in acromegaly are usually raised, not suppressed.
- C: Autoimmune beta-cell destruction causes type 1 diabetes, not acromegaly-related hyperglycemia.
Question 6 · Easy
Somatostatin, released by the delta cells of the pancreatic islets, affects the other islet hormones by:
1. AStimulating insulin release but inhibiting glucagon
2. BInhibiting insulin release but stimulating glucagon
3. CInhibiting release of both insulin and glucagon
4. DStimulating release of both insulin and glucagon
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Question 7 · Medium
In the beta cell, glucose metabolism raises the ATP/ADP ratio. How does this trigger insulin release?
1. AVoltage-gated Ca2+ channels close and calcium falls
2. BATP-sensitive K+ channels open and the cell hyperpolarizes
3. CATP-sensitive K+ channels close and the cell depolarizes
4. DATP binds insulin receptors on the beta cell itself
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Question 8 · Hard
A 16-year-old with type 1 diabetes has high fasting glucose readings. Typical overnight results: 22:00 7.8 mmol/L (140 mg/dL); 03:00 7.4 mmol/L (133 mg/dL); 07:00 12.6 mmol/L (227 mg/dL). He has no night sweats or nightmares. Which explanation fits best?
1. ASomogyi effect: rebound after hypoglycemia at night
2. BDawn phenomenon from early-morning GH and cortisol
3. CAdrenal insufficiency with a low morning cortisol
4. DGlucagonoma causing constant glucagon excess
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Question 9 · Easy
Besides increasing glucose uptake, insulin acts on the liver to stimulate:
1. AGluconeogenesis
2. BGlycogen synthesis
3. CGlycogen breakdown
4. DKetone body production
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Glucose metabolism and regulating hormones

Insulin increases glucose uptake into skeletal muscle and fat cells by moving which transporter into the cell membrane?

Oral glucose causes a much larger insulin response than intravenous glucose giving the same plasma glucose rise. This is mainly due to:

When plasma glucose starts to fall below normal, which two hormones act within minutes to raise it again?

Which adrenal hormone raises blood glucose over several hours and normally peaks in the early morning?

A 48-year-old man with acromegaly has a fasting plasma glucose of 7.6 mmol/L (137 mg/dL). Excess growth hormone raises his glucose mainly by:

Somatostatin, released by the delta cells of the pancreatic islets, affects the other islet hormones by:

In the beta cell, glucose metabolism raises the ATP/ADP ratio. How does this trigger insulin release?

A 16-year-old with type 1 diabetes has high fasting glucose readings. Typical overnight results: 22:00 7.8 mmol/L (140 mg/dL); 03:00 7.4 mmol/L (133 mg/dL); 07:00 12.6 mmol/L (227 mg/dL). He has no night sweats or nightmares. Which explanation fits best?

Besides increasing glucose uptake, insulin acts on the liver to stimulate: