Diabetes Mellitus: Biochemical Aspects Indian Medical PG Practice Questions and MCQs
Practice Indian Medical PG questions for Diabetes Mellitus: Biochemical Aspects. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
Diabetes Mellitus: Biochemical Aspects Indian Medical PG Question 1: Among the following, most reliable test for screening of diabetes mellitus?
- A. Urine sugar
- B. Random sugar
- C. Fasting sugar (Correct Answer)
- D. Glucose tolerance test
Diabetes Mellitus: Biochemical Aspects Explanation: ***Fasting sugar***
- A **fasting plasma glucose** (FPG) test is the most common and reliable initial test for screening for **diabetes mellitus** because it measures blood glucose after an overnight fast (typically 8-12 hours), providing a baseline level unaffected by recent food intake [1].
- A fasting glucose level of **≥ 126 mg/dL** (7.0 mmol/L) on two separate occasions is diagnostic of diabetes, making it an excellent screening tool for identifying individuals with impaired glucose metabolism [1].
*Random sugar*
- A random plasma glucose test can be used to diagnose diabetes if the level is **≥ 200 mg/dL** (11.1 mmol/L) in a symptomatic individual, but it is less reliable for screening asymptomatic individuals due to its variability depending on recent food intake [1].
- Because it can be measured at any time of day without regard to the last meal, it has a **lower sensitivity** for detecting early stages of diabetes compared to fasting glucose.
*Glucose tolerance test*
- An **oral glucose tolerance test** (OGTT) is highly sensitive and specific for diagnosing diabetes and impaired glucose tolerance, but it is more cumbersome and time-consuming, involving multiple blood draws over two hours after consuming a sugary drink.
- While it is a definitive diagnostic test, its complexity makes it **less practical for routine screening** in large populations compared to simpler tests like fasting plasma glucose.
*Urine sugar*
- The presence of glucose in urine (glycosuria) indicates that blood glucose levels have exceeded the **renal threshold** (typically around 180 mg/dL), meaning the kidneys are unable to reabsorb all the glucose.
- This is a **less sensitive and specific** method for screening, as it only becomes positive once blood glucose is significantly elevated, and it does not detect milder forms of impaired glucose metabolism or early diabetes.
Diabetes Mellitus: Biochemical Aspects Indian Medical PG Question 2: 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
Diabetes Mellitus: Biochemical Aspects 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.
Diabetes Mellitus: Biochemical Aspects Indian Medical PG Question 3: In type I diabetes, which of the following is the MOST characteristic metabolic change that distinguishes it from type II diabetes:-
- A. Increased protein catabolism
- B. Decreased glucose uptake
- C. Increased hepatic glucose output
- D. Increased lipolysis (Correct Answer)
Diabetes Mellitus: Biochemical Aspects Explanation: ***Increased lipolysis***
- In **type 1 diabetes** (T1D), there is an **absolute deficiency of insulin**, which is a potent **anti-lipolytic hormone**. [1]
- This lack of insulin leads to unopposed **lipolysis**, resulting in increased free fatty acid (FFA) release, which can be metabolized into **ketone bodies** and contribute to **diabetic ketoacidosis (DKA)**. [2]
*Increased protein catabolism*
- While protein catabolism is increased in uncontrolled T1D due to the lack of insulin and increased counter-regulatory hormones, it is not the *most characteristic* metabolic change that clearly distinguishes it from type 2 diabetes (T2D), especially in early stages of T2D where some insulin may still be present. [1]
- **Protein breakdown** produces amino acids for gluconeogenesis, contributing to hyperglycemia, but **lipolysis leading to ketosis** is more specific to severe insulin deficiency. [3]
*Decreased glucose uptake*
- **Decreased glucose uptake** by peripheral tissues (especially muscle and adipose tissue) is a characteristic feature of both T1D and T2D. [1]
- In T1D, it's due to insulin deficiency, while in T2D, it's primarily caused by **insulin resistance**, making it less specific to distinguish T1D.
*Increased hepatic glucose output*
- **Increased hepatic glucose output** is a significant contributor to hyperglycemia in both T1D and T2D. [1]
- In T1D, it's due to the lack of insulin's suppressive effect on the liver, whereas in T2D, it's due to **hepatic insulin resistance** and increased gluconeogenesis.
Diabetes Mellitus: Biochemical Aspects Indian Medical PG Question 4: Mr. Murali has 126 mg/dl of fasting plasma glucose. His venous plasma glucose 2h after ingestion of 75g oral glucose load is 149 mg/dl. This patient comes under which stage of WHO diagnostic criteria of diabetes & intermediate hyperglycemia?
- A. Decreased glucose resistance
- B. IFG - Impaired fasting glucose
- C. Diagnosis of diabetes (Correct Answer)
- D. Impaired glucose tolerance
Diabetes Mellitus: Biochemical Aspects Explanation: **Diagnosis of diabetes**
- The **fasting plasma glucose (FPG)** of 126 mg/dL meets the WHO criterion for **diabetes**, which is FPG ≥ 126 mg/dL [1].
- Although the 2-hour post-glucose load (149 mg/dL) falls within the **impaired glucose tolerance (IGT)** range (140-199 mg/dL), the elevated fasting glucose alone is sufficient for a diabetes diagnosis according to WHO guidelines.
*Decreased glucose resistance*
- This term is not a standard diagnostic category recognized by the WHO for glucose metabolism disorders.
- Glucose resistance is more commonly associated with conditions like **insulin resistance** rather than a specific diagnostic stage [1].
*IFG - Impaired fasting glucose*
- **Impaired fasting glucose (IFG)** is defined by a fasting plasma glucose level between 100 mg/dL and 125 mg/dL.
- Mr. Murali's fasting glucose of 126 mg/dL is higher than the upper limit for IFG [1].
*Impaired glucose tolerance*
- **Impaired glucose tolerance (IGT)** is defined by a 2-hour post-glucose load plasma glucose level between 140 mg/dL and 199 mg/dL.
- While Mr. Murali's 2-hour reading of 149 mg/dL falls within this range, the elevated fasting glucose level takes precedence for the overall diagnosis [1].
Diabetes Mellitus: Biochemical Aspects Indian Medical PG Question 5: A patient with diabetes mellitus for the past 5 years presents with vomiting and abdominal pain. She is non-compliant with medication and appears dehydrated. Investigations revealed a blood sugar value of 500 mg/dl and the presence of ketone bodies. What is the next best step in management of this patient?
- A. Intravenous fluids
- B. Intravenous insulin
- C. Intravenous fluids with regular insulin (Correct Answer)
- D. Intravenous fluids with long-acting insulin
Diabetes Mellitus: Biochemical Aspects Explanation: Detailed management of diabetic ketoacidosis (DKA) requires both fluid resuscitation and insulin therapy.
***Intravenous fluids with regular insulin***
- The patient presents with classic signs of **diabetic ketoacidosis (DKA)**: hyperglycemia (blood sugar 500 mg/dl), ketone bodies, dehydration, and a history of diabetes non-compliance [1].
- Initial management for DKA involves aggressive **intravenous fluid resuscitation** to correct dehydration and then **intravenous regular insulin** to lower blood glucose and resolve ketosis [2].
*Intravenous fluids with long-acting insulin*
- While fluids are essential, **long-acting insulin** is not appropriate for the acute management of DKA because its slow onset of action makes it inefficient for rapidly correcting hyperglycemia and ketosis.
- **Regular insulin** is preferred as it has a quicker onset and shorter duration, allowing for more precise titration in an acute setting [2].
*Intravenous fluids*
- Although crucial for correcting **dehydration** and improving renal perfusion, fluids alone will not address the underlying **insulin deficiency** and **ketosis** that define DKA.
- Without insulin, the body will continue to produce ketones, exacerbating acidosis [3].
*Intravenous insulin*
- Giving intravenous insulin without prior or concomitant **fluid resuscitation** can be dangerous, as it can worsen **hypovolemia** and potentially lead to circulatory collapse by shifting glucose and potassium into cells.
- It is critical to first restore **circulating volume** before initiating insulin therapy [2].
Diabetes Mellitus: Biochemical Aspects Indian Medical PG Question 6: Agent that acts through tyrosine kinase receptor is
- A. Insulin (Correct Answer)
- B. MSH
- C. TSH
- D. TRH
Diabetes Mellitus: Biochemical Aspects Explanation: ***Insulin***
- **Insulin** binds to its receptor, which is a **tyrosine kinase receptor**, leading to autophosphorylation and the activation of intracellular signaling pathways.
- This activation is crucial for glucose uptake and metabolism by various cells in the body.
*MSH*
- **Melanocyte-stimulating hormone (MSH)** acts primarily through **G protein-coupled receptors**, specifically melanocortin receptors.
- These receptors activate adenylyl cyclase, leading to an increase in intracellular cAMP.
*TSH*
- **Thyroid-stimulating hormone (TSH)** also acts via a **G protein-coupled receptor** on thyroid follicular cells.
- Its binding stimulates adenylyl cyclase, increasing cAMP and thus thyroid hormone synthesis and release.
*TRH*
- **Thyrotropin-releasing hormone (TRH)** binds to **G protein-coupled receptors** on pituitary thyrotrophs.
- This interaction activates the phospholipase C pathway, leading to the release of TSH.
Diabetes Mellitus: Biochemical Aspects Indian Medical PG Question 7: Ketone body formation without glycosuria is seen in ?
- A. Diabetes mellitus
- B. Diabetes insipidus
- C. Starvation (Correct Answer)
- D. Obesity
Diabetes Mellitus: Biochemical Aspects Explanation: ***Starvation***
- During **starvation**, the body depletes its **glycogen stores** and begins to break down **fat for energy**. This process leads to the production of **ketone bodies** (acetoacetate, beta-hydroxybutyrate, and acetone) as an alternative fuel source for the brain and other tissues.
- Since there is no underlying problem with **insulin production** or action, blood glucose levels are typically low or normal, and therefore, **glycosuria** (glucose in the urine) is absent.
*Diabetes mellitus*
- In **uncontrolled diabetes mellitus**, especially Type 1, the body cannot effectively use **glucose** due to lack of insulin, leading to high blood glucose levels (**hyperglycemia**) and subsequently **glycosuria**.
- The body then compensates by breaking down **fats**, leading to the formation of **ketone bodies** (**diabetic ketoacidosis**), which results in both **ketonuria** and **glycosuria**.
*Diabetes insipidus*
- **Diabetes insipidus** is a condition characterized by the inability to conserve water due to insufficient **antidiuretic hormone (ADH)** production or action, leading to excessive urination and thirst.
- It does not involve abnormalities in **glucose metabolism** or **ketone body production** and therefore does not typically present with ketonuria or glycosuria.
*Obesity*
- While **obesity** can lead to **insulin resistance** and is a risk factor for Type 2 Diabetes, it does not directly cause **ketone body formation** in the absence of metabolic derangements such as those seen in uncontrolled diabetes or prolonged starvation.
- In most cases of obesity without diabetes, **glucose metabolism** is still adequate enough to prevent significant reliance on **fat breakdown** for energy, meaning there is usually no ketonuria or glycosuria.
Diabetes Mellitus: Biochemical Aspects Indian Medical PG Question 8: Glycemic index is defined as:
- A. Glucose control in last 3 months
- B. Measure of the change in the blood glucose following ingestion of proteins
- C. Measure of the change in the blood glucose following ingestion of fats
- D. Measure of the change in blood glucose following the ingestion of carbohydrates. (Correct Answer)
Diabetes Mellitus: Biochemical Aspects Explanation: ***Measure of the change in blood glucose following the ingestion of carbohydrates.***
- The **glycemic index (GI)** specifically quantifies how much a particular **carbohydrate-containing food** raises blood glucose levels compared to a reference food (pure glucose or white bread).
- This value reflects the rate at which **carbohydrates** are digested and absorbed into the bloodstream.
*Glucose control in last 3 months*
- This description refers to **HbA1c (glycated hemoglobin)**, which provides an average blood glucose level over the preceding 2-3 months.
- HbA1c is a clinical measure of long-term glycemic control, not a property of individual foods.
*Measure of the change in the blood glucose following ingestion of proteins*
- While proteins can affect blood glucose, their impact is generally much smaller and slower compared to carbohydrates, and it's not what the **glycemic index** measures.
- The primary role of protein in glucose metabolism is through **gluconeogenesis** or an insulin response, which is distinct from the immediate post-prandial glucose spike from carbohydrates.
*Measure of the change in the blood glucose following ingestion of fats.*
- Fats have a minimal direct impact on blood glucose levels; they are primarily digested into fatty acids and glycerol.
- Although fats can slow down gastric emptying and carbohydrate absorption, they do not directly cause a significant rise in blood glucose and are not considered in the definition of the **glycemic index**.
Diabetes Mellitus: Biochemical Aspects Indian Medical PG Question 9: Obesity has the maximum relative risk for which condition?
- A. Cancer
- B. DM (Correct Answer)
- C. Hypertension
- D. CHD
Diabetes Mellitus: Biochemical Aspects Explanation: ***DM***
- Obesity is a major risk factor for **type 2 diabetes mellitus (DM)**, significantly increasing insulin resistance and pancreatic beta-cell dysfunction.
- The relative risk for developing type 2 diabetes attributable to obesity is generally considered to be among the **highest compared to other chronic diseases**.
*Cancer*
- Obesity is linked to an increased risk of several cancers, including colorectal, breast, and endometrial cancers due to chronic inflammation and hormonal changes.
- While significant, the relative risk of obesity for cancer is typically **lower than for type 2 diabetes**.
*Hypertension*
- Obesity contributes to **hypertension** by activating the sympathetic nervous system and renin-angiotensin-aldosterone system.
- Although there is a strong association, the relative risk for hypertension due to obesity is generally **not as high as for type 2 diabetes**.
*CHD*
- Obesity is a significant risk factor for **coronary heart disease (CHD)** through its association with dyslipidemia, hypertension, and diabetes.
- The relative risk for CHD is substantial, but **indirectly mediated** by other comorbid conditions, and the direct relative risk is often surpassed by that of type 2 diabetes.
Diabetes Mellitus: Biochemical Aspects Indian Medical PG Question 10: A 24-year-old woman presents with recurrent vulvovaginal candidiasis. Which condition should be considered?
- A. Diabetes mellitus (Correct Answer)
- B. Hypertension
- C. Hypothyroidism
- D. Hyperlipidemia
Diabetes Mellitus: Biochemical Aspects Explanation: ***Diabetes mellitus***
- **Uncontrolled blood sugar** provides a rich environment for *Candida* overgrowth, leading to recurrent infections [1].
- Impaired immune response in diabetes also makes individuals more susceptible to **opportunistic fungal infections** [1].
*Hypertension*
- **Hypertension** is a cardiovascular condition characterized by elevated blood pressure and is not directly linked to fungal infections.
- It does not significantly alter the vaginal microenvironment or immune response in a way that would predispose to recurrent candidiasis.
*Hypothyroidism*
- **Hypothyroidism** involves insufficient thyroid hormone production and can cause symptoms like fatigue and weight gain.
- There is no direct physiological link between thyroid hormone levels and susceptibility to vulvovaginal candidiasis.
*Hyperlipidemia*
- **Hyperlipidemia** is characterized by high levels of lipids (fats) in the blood and is a risk factor for cardiovascular disease.
- This condition does not create a predisposition to recurrent *Candida* infections.
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