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Q76 - Insulin and Glucagon Dynamics in Type 2 Diabetes

Theoretical 2 Real exam question - full text reproduced under IBO's CC BY-NC-SA 4.0 license
Endocrine System Physiology

Insulin and glucagon hormones are synthesized in the islets of the pancreas. The balance of their production ensures a stable level of glucose in the blood. Increased glucose levels stimulate the production of insulin by β-cells, while in hypoglycemia, glucagon is released by α cells.

Three-panel figure showing glucose, insulin, and glucagon levels over time (-60 to 300 minutes) around a meal, comparing healthy (“Normal”) individuals to those with type 2 diabetes (T2DM). Glucose: Normal rises modestly from ~100 to ~150 mg/ml then returns to baseline; T2DM stays elevated the whole time, rising from ~220 to ~310 and declining only slightly. Insulin: Normal shows a large biphasic peak reaching ~140 mg/ml; T2DM shows a much smaller, blunted peak reaching only ~45-50 mg/ml. Glucagon: Normal drops from ~120 to ~75-80 mg/ml after the meal before recovering; T2DM instead rises from ~120 to ~145 mg/ml after the meal and stays elevated. Changes in glucose, insulin and glucagon levels in healthy individuals (“Normal”) and individuals with type 2 diabetes (T2DM), before and after a meal.

Based on this biochemical analysis, determine whether the following statements are true or false.

A. The increase in glucose levels in the plasma of healthy people after a meal is due to heightened glucagon levels.
B. The increase in glucose levels in the plasma leads to a more pronounced increase in insulin levels in type 2 diabetes (T2DM) patients than in healthy individuals.
C. Glucagon production in healthy people is suppressed by an increase in glucose levels in plasma and by subsequent stimulation of insulin production.
D. In T2DM patients, the suppressive effect of glucose on glucagon disappears, and may even be replaced by the stimulation of glucagon production.
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Question reproduced from IBO 2022, Theoretical Paper 2, licensed under CC BY-NC-SA 4.0 - attributed to the International Biology Olympiad. Open the full exam PDF · Community solutions (unofficial)