Diabetes Mellitus & Hypoglycemia with Management

Question 1

What is the primary problem in energy metabolism due to intermittent eating?

Answer 1

Tissues need energy all the time to survive, but we eat intermittently.

Question 2

What are the main hormones involved in energy storage during feeding?

Answer 2

Insulin stores excess energy.

Question 3

What hormones are involved in mobilizing nutrients during fasting?

Answer 3

Glucagon, Adrenaline, Cortisol, Growth Hormone.

Question 4

What are the primary sources of insulin and glucagon in the pancreas?

Answer 4

Insulin is produced by β-cells (75% of pancreatic cells) and glucagon by α-cells (20% of pancreatic cells).

Question 5

What are the key differences in insulin and glucagon secretion stimuli?

Answer 5

Insulin secretion is stimulated by high glucose, while glucagon secretion is stimulated by low glucose.

Question 6

What metabolic syndrome indicators suggest a higher risk for diabetes?

Answer 6

Waist circumference ≥ 90 cm (men) or ≥ 80 cm (women), High triglycerides ≥ 1.7 mmol/L, High fasting glucose ≥ 6.1 mmol/L, High blood pressure ≥ 130/85 mmHg, Low HDL cholesterol ≤ 1.0 mmol/L (men) or ≤ 1.3 mmol/L (women).

Question 7

What is the diagnostic criteria for Diabetes Mellitus based on plasma glucose?

Answer 7

Fasting glucose: DM if >7.0 mmol/L
OGTT (2h): DM if >11.1 mmol/L
HbA1C: DM if >6.9%

Question 8

What is the role of adipose tissue in metabolic syndrome?

Answer 8

Adipose tissue dysfunction can lead to persistent low-grade inflammation (due to M1 Macrophages) and insulin resistance.

Question 9

How is OGTT used in diagnosing hormone-secreting pituitary tumors?

Answer 9

In acromegaly, a glucose tolerance test is used where growth hormone levels >0.4 µg/liter after glucose ingestion suggest the need for further evaluation.

Question 10

What is the central feature of Diabetes Mellitus (DM)?

Answer 10

High plasma glucose concentration.

Question 11

What are the types and causes of Diabetes Mellitus?

Answer 11

Type 1: Autoimmune (genetic).
Type 2: Multifactorial (genetics & lifestyle).

Question 12

What are the acute effects of Diabetes Mellitus?

Answer 12

High plasma glucose.
Accumulation of ketone bodies (Type 1).

Question 13

What are the chronic complications of Diabetes Mellitus?

Answer 13

Eye: Retinopathy leading to blindness.
Kidneys: Nephropathy leading to kidney failure.
Blood vessels: Atherosclerosis leading to heart attacks, stroke, gangrene.
Nerves: Neuropathy causing various problems.

Question 14

What is Diabetic Ketoacidosis (DKA) and which type of diabetes is it associated with?

Answer 14

DKA is a severe form of metabolic acidosis due to excessive ketone production, associated with Type 1 Diabetes.

Question 15

What is the diagnostic criteria for hypoglycemia?

Answer 15

Mild: 3.0 – 3.9 mM.
Moderate: 2.2 – 2.9 mM.
Severe: <2.2 mM.

Question 16

What are the effects of hypoglycemia at different glucose levels?

Answer 16

4.4 mM (80 mg/dL): ↓ Insulin.
3.9 mM (70 mg/dL): ↑ Glucagon and adrenaline.
3.3 mM (60 mg/dL): ↑ Cortisol and growth hormone.
2.8 mM (50 mg/dL): Cognitive impairment.
2.2 mM (40 mg/dL): Weakness, ataxia, lethargy.
1.7 mM (30 mg/dL): Coma.
1.1 mM (20 mg/dL): Convulsions.
0.6 mM (10 mg/dL): Irreversible brain damage and death.

Question 17

What are the causes of hypoglycemia?

Answer 17

Insulin excess.
Deficiency of counter-regulatory hormones.
Impaired glucose generation.
Others: Insulinoma, alcohol, liver/renal failure.

Question 18

What are the long-term complications of Diabetes Mellitus?

Answer 18

Retinopathy: Blindness.
Nephropathy: Kidney failure.
Neuropathy: Various problems.
Atherosclerosis: Heart attacks, stroke, gangrene.

Question 19

What are secondary causes of diabetes?

Answer 19

Monogenic diabetes.
Pancreatic disorders.
Endocrine disorders.
Drug-induced diabetes.
Immune-mediated diabetes.
Genetic syndromes.
Gestational diabetes.

Question 20

Which of the following directly stimulates mitosis?
A.insulin
B.somatotropin
C.corticotropin
D.growth hormone releasing hormone

Answer 20

B: Both insulin and somatotropin (GH) can stimulate mitosis. However, insulin only stimulates mitosis via IGF-1 but GH can stimulate mitosis on its own and via IGF-1.

Question 21

The hormone _____ causes the breast to increase its synthesis of milk.
A.prolactin
B.oxytocin
C.PRF
D.PIF

Answer 21

A: Prolactin increases synthesis of milk. Oxytocin increases secretion of milk.

Question 22

Which of the following is not true of T3?
A.needed for normal mental growth
B.increases carbohydrate utilization
C.decreases lipid synthesis
D.decreases protein synthesis

Answer 22

The correct answer is:
D. decreases protein synthesis
Here’s why:
Thyroid Hormones and Brain Development
Thyroid hormones, especially T3, are essential for normal brain development and function. T3 influences many aspects of neural cell migration, differentiation, and signaling. It enters the brain through specific transporters and acts on nuclear receptors to control the expression of genes involved in myelination, cell differentiation, migration, and signaling.
Effects of T3 on Metabolism
T3 increases carbohydrate utilization by stimulating glycolysis and glucose oxidation. It also enhances lipid metabolism by increasing fatty acid oxidation and decreasing lipid synthesis.
However, T3 does not decrease protein synthesis. In fact, it has the opposite effect - T3 increases protein synthesis by enhancing amino acid transport and activating protein synthesis pathways.
Therefore, the statement “T3 decreases protein synthesis” is incorrect, while the other options are true effects of T3.

Question 23

Graves disease can cause all of these except which one?
A.exophthalmos (popping out eyes)
B.a positive autoimmune test
C.general edema
D.intolerance to heat

Answer 23

C: Graves’ Disease causes exophthalmos or eye proptosis due to the Thyroid Stimulating Immunoglobulins (TSIs) causing inflammation and edamatous swelling of the retro-orbital tissue. Since Graves’ Disease is an autoimmune disease by immunoglobulin, there will also be a positive autoimmune test. Graves’ Disease is a form hyperthyroidism and thus, an increase in metabolic rate and body temperature. This results in an intolerance of heat. Graves’ Disease does not cause general edema.

Question 24

The hormone melatonin is secreted from the _____ gland.
A.pituitary
B.pineal
C.thyroid
D.thymus

Answer 24

B

Question 25

Hypothyroidism
A) Usually caused by a lack of thyroid-stimulating hormone
B) Can be diagnosed by measuring serum T3
C) is often associated with a low plasma calcium concentration
D) ?
E) Short stature

Answer 25

78. E: Hypothyroidism is usually caused by thyroiditis (infections that damage the thyroid gland) or iodine deficiency, not the lack of TSH. It cannot be diagnosed by measuring serum T3 because it does not reflect the state of the thyroid gland well due to the conversion of T4 to T3 at target sites. Instead, serum T4 is a better indicator. Parathyroid hormone is the hormone associated with low plasma calcium concentration. Low [Ca2+] increases parathyroid hormone secretion. Hypothyroidism results in short stature due to thyroid hormone’s effect on increasing GH.

Question 26

Calcium
A) is more than 90% bound to protein in the circulation
B) level in the blood is usually very low in patients with calcitonin-producing tumours
C) binds to a calcium-sensing receptor in parathyroid gland cells to suppress parathyroid hormone production
D) concentration in blood has no effect on calcitonin secretion
E) absorption by the intestine is decreased by calcitonin

Answer 26

C: Tough question. Calcium is usually stored in the bones. 40% of circulating calcium is protein bound, 10% is complexed with other anions while 50% is ionized and active. Calcitonin is relatively weak in its effects, therefore calcitonin-producing tumours do not result in significant reduction of calcium levels in blood. It effects are, majorly, decrease in renal reabsorption of calcium and increases calcium deposition in bone. Calcitonin is stimulated by low Ca2+ in blood. Calcium is regulated by parathyroid hormone and regulates the levels of PTH via calcium-sensing receptors on parathyroid gland cells.

Question 27

A middle-aged man has lung cancer. His plasma sodium concentration is 125mmol/L (normal range: 135-145), his plasma osmolality is 265 mOsm/kg (normal range: 280-295), his urine osmolality is 650 mOsm/kg (normal range: 650-1200). What is the most likely problem?
A) Aldosterone production was increased due to metastasis of the cancer to the adrenal glands.
B) There was polydipsia due to spread of the cancer to the thirst center of the hypothalamus.
C) There was an excess secretion of Na+
D) There was an excess ADH production
E) There is excessive sodium loss in the urine because of kidney damage

Answer 27

83. D: Hyponatremia. Hypoosmotic plasma. Urine osmolality seems normal. This seem to indicate that aldosterone and ADH aren’t involved since aldosterone causes isosmotic volume expansion while ADH causes reabsorption of water ONLY via aquaporin expression in the collecting duct, which should increase urine osmolality. However, we are looking at a condition known as oat cell carcinoma in this case, which occurs in the lungs. These malignant tumours produce excessively uncontrolled amounts of ADH, resulting in Syndrome of Inappropriate ADH secretion (SIADH). Other types of malignant cells that can result in SIADH can occur at the pancreas, prostate, thymus or lymphoma. At this juncture, how do we account for the seemingly normal urine osmolality? Firstly, urine osmolality is highly variable as seen from the large range given. In fact, for a urine to be considered concentrated, the criteria needed is Na+ > 20mmol/L and osmolality > 100mosm/kg. In this case, it is evident that 650mosm/kg already crosses the given value. While B might seem like a better possible answer as polydipsia can also occur if the hypothalamus is damaged and even results in hypoosmolar urine, the fact is that it is very unlikely that lung cancer can cause damage to the hypothalamus. Given that, we choose D as the best answer.

Question 28

Thyroxine
A. Is increased due to increased tsh in graves disease
B. T3 acts by cAMP linked receptor on plasma membrane
C. Deficiency in natal life before age of 3 will not lead to mental retardation
D. Defiency due to lack of iodine will not lead to goiter
E. Is converted to t3 in liver and other cells

Answer 28

E: Thyroxine is increased in Graves’ Disease due to Thyroid Stimulating Immunoglobulins (autoimmune condition). Being a thyroid hormone, its receptors are in the nucleus, in close proximity to the target genes. Consequently, it does not act by cAMP linked receptors. Deficiency in natal life before 3 does lead to mental retardation and iodine deficiency results in goiter due to T3 and T4 deficiency and thus, increase in TSH secretion that stimulates growth of thyroid gland. Most thyroid hormones (93%) exist as T4 which are converted to the active T3 at the target cells.