Glucose Tolerance Tests — MCQs
In Type 1 Diabetes Mellitus (DM) stage 3 beta cell destruction, which of the following is the most likely presentation?
Which assay is primarily used to assess growth hormone levels?
Stress hyperglycemia occurs due to all except -
The diagnosis of diabetes mellitus is certain in which of the following situations?
In infants of diabetic mothers (IDM), when is ophthalmologic evaluation indicated?
Low osmolarity ORS - false statement is
Hyperglycemia occurs after what % of beta cell mass is destroyed:
TRH stimulation testing is useful in diagnosis of disorders of the following hormones?
The "cutoff" value of plasma glucose in a 50-g glucose challenge test is
Which test produces characteristic crystals for the detection of semen?
Glucose Tolerance Tests Indian Medical PG Practice Questions and MCQs
Question 1: In Type 1 Diabetes Mellitus (DM) stage 3 beta cell destruction, which of the following is the most likely presentation?
- A. Dysglycemic symptomatic
- B. Normoglycemic symptomatic
- C. Dysglycemic asymptomatic
- D. Hyperglycemia symptomatic (Correct Answer)
- E. Normoglycemic asymptomatic
Explanation: ***Hyperglycemia symptomatic*** - **Type 1 DM stage 3** is characterized by sufficient **beta-cell destruction** to cause overt hyperglycemia. - This level of hyperglycemia typically leads to classic symptoms such as **polyuria, polydipsia, and weight loss**. *Dysglycemic symptomatic* - **Dysglycemic** refers to abnormal blood sugar levels, but this term is too broad and doesn't specify the degree or symptomatic nature as precisely as **hyperglycemia symptomatic**. - While patients are symptomatic, the primary issue is **hyperglycemia**, making that a more specific and accurate description. *Normoglycemic symptomatic* - **Normoglycemic** implies normal blood sugar levels, which is inconsistent with **Type 1 DM stage 3** where significant beta-cell destruction has occurred. - This stage is defined by definite hyperglycemia, so a patient cannot be symptomatic while having normal glucose levels due to the disease. *Dysglycemic asymptomatic* - While there is **dysglycemia**, **asymptomatic presentation** is more characteristic of earlier stages (Type 1 DM stage 2), where hyperglycemia is present but not yet severe enough to cause overt symptoms. - In **stage 3**, beta-cell destruction is substantial, leading to glucose levels that are high enough to cause noticeable symptoms. *Normoglycemic asymptomatic* - **Normoglycemic asymptomatic** describes **Type 1 DM stage 1**, where autoimmunity is present but beta-cell destruction has not yet progressed enough to affect glucose levels. - This is the earliest stage of Type 1 DM, well before the overt hyperglycemia seen in stage 3.
Question 2: Which assay is primarily used to assess growth hormone levels?
- A. Diabetes mellitus
- B. Glucagon assay
- C. Growth hormone stimulation test (Correct Answer)
- D. Catecholamines
Explanation: ***Growth hormone stimulation test*** - This is the primary diagnostic assay to evaluate **growth hormone (GH) deficiency** or excess, as GH levels fluctuate throughout the day. - Various stimuli, such as **insulin-induced hypoglycemia**, **arginine**, or **clonidine**, are used to trigger GH release, and levels are measured serially [1]. *Diabetes mellitus* - This is a metabolic disorder characterized by **elevated blood glucose levels** due to insulin deficiency or resistance, not an assay for growth hormone. - While growth hormone can affect glucose metabolism, diabetes mellitus describes a **disease state**, not a diagnostic test for growth hormone levels [2]. *Glucagon assay* - A glucagon assay measures the level of **glucagon**, a hormone produced by the pancreas that raises blood glucose levels. - While glucagon can be used in some stimulation tests for growth hormone, a "glucagon assay" alone is not the primary method to assess overall growth hormone status. *Catecholamines* - Catecholamines are a group of hormones, including **epinephrine (adrenaline)**, **norepinephrine**, and **dopamine**, which are involved in the body's stress response. - Assays for catecholamines are used to diagnose conditions like **pheochromocytoma** or neuroblastoma, not to assess growth hormone levels.
Question 3: Stress hyperglycemia occurs due to all except -
- A. Increased level of ACTH
- B. Decreased level of norepinephrine (Correct Answer)
- C. Insulin resistance
- D. Increased level of cortisol
Explanation: ***Decreased level of norepinephrine*** - **Norepinephrine** is a **catecholamine** that generally **increases blood glucose** by stimulating **glycogenolysis** and **gluconeogenesis**. - Therefore, a *decrease* in norepinephrine would *reduce* stress-induced hyperglycemia, making this the exception. *Increased level of ACTH* - **ACTH (Adrenocorticotropic Hormone)** stimulates the adrenal glands to release **cortisol**, which contributes significantly to stress hyperglycemia. - Increased ACTH levels therefore *promote* hyperglycemia in stress. *Insulin resistance* - **Insulin resistance** is a common feature during stress, where target cells become less responsive to insulin's effects. - This reduced insulin sensitivity leads to higher circulating glucose levels, contributing to hyperglycemia. *Increased level of cortisol* - **Cortisol** is a key **stress hormone** that promotes **gluconeogenesis** (production of glucose from non-carbohydrate sources) and **glycogenolysis** (breakdown of glycogen to glucose). - Elevated cortisol levels directly lead to an increase in blood glucose, causing hyperglycemia.
Question 4: The diagnosis of diabetes mellitus is certain in which of the following situations?
- A. Abnormal oral glucose tolerance in a 24-yrs-old woman who has been dieting
- B. A serum glucose level >7.8 mmol/L in a woman in her twenty-fifth week of gestation after a 50-g oral glucose load
- C. Persistent asymptomatic glycosuria in a 30-yrs-old woman
- D. Successive fasting plasma glucose concentrations of 8, 9, and 8.5 mmol/L in an asymptomatic, otherwise healthy individual. (Correct Answer)
Explanation: ***Successive fasting plasma glucose concentrations of 8, 9, and 8.5 mmol/L in an asymptomatic, otherwise healthy individual.*** - A definitive diagnosis of **diabetes mellitus** requires two separate fasting plasma glucose (FPG) levels of **≥7.0 mmol/L** (126 mg/dL) or higher [1]. The given values (8, 9, 8.5 mmol/L) meet this criterion. - Since the individual is **asymptomatic**, two abnormal tests are typically needed to confirm the diagnosis, which is satisfied by the successive elevated fasting glucose levels. *Abnormal oral glucose tolerance in a 24-yrs-old woman who has been dieting* - **Dieting** can affect glucose metabolism and potentially lead to an abnormal oral glucose tolerance test (OGTT) result that does not accurately reflect diabetes. - A single abnormal OGTT in a dieting individual without confirmatory tests or symptoms is not sufficient for a definitive diagnosis of diabetes. *A serum glucose level >7.8 mmol/L in a woman in her twenty-fifth week of gestation after a 50-g oral glucose load* - A serum glucose level >7.8 mmol/L after a **50-g glucose challenge** is a positive screening test for **gestational diabetes mellitus**, but it is not diagnostic [2]. - A positive screening test requires further confirmation with a **100-g or 75-g oral glucose tolerance test** to diagnose gestational diabetes. *Persistent asymptomatic glycosuria in a 30-yrs-old woman* - **Glycosuria** (glucose in the urine) without hyperglycemia (elevated blood glucose) can be due to a low **renal threshold for glucose**, a benign condition called renal glycosuria. - While it warrants investigation for diabetes, persistent asymptomatic glycosuria alone is **not diagnostic** of diabetes unless accompanied by elevated blood glucose levels.
Question 5: In infants of diabetic mothers (IDM), when is ophthalmologic evaluation indicated?
- A. At the time of diagnosis
- B. Only if visual symptoms develop (Correct Answer)
- C. After 5 years routinely
- D. After developing diabetes
Explanation: ***Only if visual symptoms develop*** - Unlike **retinopathy of prematurity**, infants of diabetic mothers (IDMs) do not have a higher incidence of **retinopathy** or other **ocular abnormalities** at birth or in early infancy. - **Ophthalmologic evaluation** is generally reserved for IDMs who develop specific **visual symptoms** or signs of ocular pathology. *At the time of diagnosis* - Routine ophthalmologic screening at the time of diagnosis of IDM is **not standard practice**, as the risk of **congenital ocular anomalies** is not substantially elevated to warrant universal screening. - Initial management focuses on metabolic stability, especially **glucose control**, and screening for other common IDM-related complications like **cardiac defects** or **respiratory distress**. *After 5 years routinely* - There is **no evidence or recommendation** for routine ophthalmologic screening of IDMs specifically at the age of 5 years. - Regular **well-child check-ups** include basic vision screening, which would identify significant refractive errors or strabismus, but not specifically for diabetes-related ocular issues. *After developing diabetes* - While it is true that individuals with **type 1 or type 2 diabetes** require regular **ophthalmologic evaluations** for **diabetic retinopathy**, this refers to the child developing diabetes later in life, not being an IDM. - Being an IDM is a **risk factor for developing diabetes** later in life, but it doesn't automatically mean they have diabetes-related ocular issues from birth.
Question 6: Low osmolarity ORS - false statement is
- A. Sodium concentration 75 mmol/liter
- B. Osmolarity is 311 mosm/liter (Correct Answer)
- C. Potassium is 20 mmol/liter
- D. Glucose concentration 75 mmol/liter
Explanation: ***Osmolarity is 311 mosm/liter*** - Low osmolarity ORS has an osmolarity of **245 mOsm/L**, calculated as: **Sodium 75 + Potassium 20 + Chloride 65 + Glucose 75 + Citrate 10 = 245 mOsm/L**. - An osmolarity of **311 mOsm/L** corresponds to the **standard WHO ORS**, not the low osmolarity ORS which was developed to reduce osmotic load. *Sodium concentration 75 mmol/liter* - This statement is **true** for low osmolarity ORS, as its sodium concentration is indeed **75 mmol/L**. - The reduced sodium concentration (compared to **90 mmol/L** in standard ORS) helps achieve the lower overall osmolarity. *Potassium is 20 mmol/liter* - This statement is **true** for low osmolarity ORS, as it contains **20 mmol/L of potassium**. - Potassium is crucial for replacing **electrolyte losses** in diarrhea and maintaining intracellular fluid balance. *Glucose concentration 75 mmol/liter* - This statement is also **true** for low osmolarity ORS, with a glucose concentration of **75 mmol/L (13.5 g/L)**. - The glucose promotes **sodium-glucose co-transport** in the intestine, facilitating water absorption despite lower sodium concentration.
Question 7: Hyperglycemia occurs after what % of beta cell mass is destroyed:
- A. 40%
- B. 80% (Correct Answer)
- C. 60%
- D. 20%
Explanation: ***80%*** - **Hyperglycemia** typically manifests only after a significant portion of **beta cell mass** (around 80-90%) has been destroyed. - This extensive loss of **insulin-producing cells** compromises the body's ability to maintain normal glucose levels [1]. *20%* - A 20% destruction of beta cell mass is generally **insufficient** to cause clinical hyperglycemia. - The remaining beta cells can usually compensate for this relatively small loss through increased insulin secretion. *40%* - While 40% loss represents a considerable reduction, it's often still within the compensatory capacity of the pancreas. - At this stage, individuals might experience **impaired glucose tolerance** but not overt hyperglycemia [1]. *60%* - Even with a 60% loss, the body may still be able to maintain near-normal glucose levels, especially in the early stages of beta cell destruction [1]. - Hyperglycemia is more likely to develop as the destruction progresses beyond this point.
Question 8: TRH stimulation testing is useful in diagnosis of disorders of the following hormones?
- A. PTH
- B. ACTH
- C. Insulin
- D. Growth hormone (Correct Answer)
Explanation: ***Growth hormone*** - **TRH** (Thyrotropin-Releasing Hormone) normally stimulates the release of **TSH** and **prolactin** from the anterior pituitary, but **does not normally affect growth hormone**. - In certain pathological conditions like **acromegaly**, TRH can **paradoxically stimulate growth hormone release**, where GH levels abnormally increase instead of remaining unchanged. - This **paradoxical GH response to TRH** is used as a diagnostic test in suspected acromegaly patients, helping differentiate it from normal physiology. - Note: The primary uses of TRH stimulation are for assessing **TSH** (thyroid axis disorders) and **prolactin** (hyperprolactinemia), but among the given options, growth hormone is the relevant answer. *PTH* - **PTH** (Parathyroid Hormone) regulation is primarily controlled by **serum calcium levels**, not by TRH. - Disorders of PTH are diagnosed through **calcium, phosphate, and PTH measurements**, not TRH stimulation. *ACTH* - **ACTH** (Adrenocorticotropic Hormone) release is stimulated by **CRH** (Corticotropin-Releasing Hormone), not TRH. - Conditions involving ACTH are typically evaluated using **CRH stimulation tests** or **dexamethasone suppression tests**. *Insulin* - **Insulin** secretion by pancreatic beta cells is primarily regulated by **blood glucose levels**, not by TRH. - Insulin-related disorders are diagnosed through **glucose tolerance tests**, **C-peptide levels**, and **insulin measurements**.
Question 9: The "cutoff" value of plasma glucose in a 50-g glucose challenge test is
- A. 120 mg/dL
- B. 140 mg/dL (Correct Answer)
- C. 160 mg/dL
- D. 180 mg/dL
Explanation: ***140 mg/dL*** - A plasma glucose level of **140 mg/dL** (7.8 mmol/L) or higher one hour after a **50-g glucose challenge** is considered abnormal and warrants further investigation with a 3-hour oral glucose tolerance test (OGTT). - This cutoff helps identify individuals at risk for **gestational diabetes mellitus (GDM)**. *120 mg/dL* - This value is below the established cutoff for an abnormal 50-g glucose challenge test. - A plasma glucose level of 120 mg/dL one hour after glucose intake is generally considered within the **normal range** for this screening test. *160 mg/dL* - While 160 mg/dL is an elevated value, the standard cutoff used to indicate a positive screen is 140 mg/dL. - Using a higher cutoff like 160 mg/dL would **decrease the sensitivity** of the screening test, potentially missing cases of gestational diabetes. *180 mg/dL* - A plasma glucose level of 180 mg/dL is significantly elevated and would certainly lead to further testing. - However, the American College of Obstetricians and Gynecologists (ACOG) and other major organizations recommend the **140 mg/dL cutoff** for initial screening to maximize sensitivity.
Question 10: Which test produces characteristic crystals for the detection of semen?
- A. Acid phosphatase test
- B. Florence test
- C. Barberio's test (Correct Answer)
- D. PSA test
Explanation: ***Barberio's test*** - This test is specifically used for the **microscopic detection of seminal fluid** by producing **characteristic spermine picrate crystals**. - It involves the addition of a **saturated picric acid solution** to a semen stain extract, leading to the formation of distinct **yellow, needle-like crystals** that are diagnostic. - It is a **confirmatory microscopic crystal test** that provides visual evidence of semen presence. *Acid phosphatase test* - This is a **presumptive test for semen** that relies on the detection of high levels of acid phosphatase, an enzyme found in seminal fluid. - While it indicates the *possible* presence of semen, it is **not confirmatory** as acid phosphatase can be found in other bodily fluids and vegetable matter. - Does **not produce crystals** for identification. *Florence test* - The Florence test is a **presumptive crystal test** that detects choline in semen, forming dark brown, rhombic crystals of choline periodide. - However, it is **not specific for semen** because choline can be found in other biological materials and vaginal secretions. - Less reliable than Barberio's test for semen confirmation. *PSA test* - The **prostate-specific antigen (PSA) test** is a highly specific **immunological confirmatory test** for human semen. - It detects the glycoprotein PSA (P30) produced by the prostate gland. - However, it does **not produce crystals** and uses different methodology (immunochromatography/ELISA).
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