Which process is most affected in individuals with type 1 diabetes?

UPRVUNL - 2021

Biochemistry & Nutrition

Medium

Appeared in: UPRVUNL - 2021

Explanation

In Type 1 Diabetes, the absolute lack of insulin means its primary anabolic (storage) functions are lost.
Glycogenesis, the formation of glycogen from glucose in the liver and muscles, is directly dependent on insulin to activate the key enzyme, glycogen synthase.
Without insulin, this glucose storage pathway is severely inhibited, making it the most profoundly affected process compared to others which may adapt or become hyperactive.
This failure of glucose storage is a primary reason for the hallmark hyperglycemia seen in uncontrolled T1DM.

Option A: The Lactic acid cycle (Cori cycle) is not inhibited; it is often hyperactive in T1DM. The liver attempts to convert lactate back to glucose (gluconeogenesis) to combat perceived cellular starvation, which worsens hyperglycemia.
Option B: While glycolysis is reduced in insulin-dependent tissues (muscle, fat), it is not the most affected process. It continues unimpeded in insulin-independent tissues like the brain, which relies on glucose for energy.
Option D: The Krebs cycle remains functional. It adapts to the lack of intracellular glucose by utilizing acetyl-CoA derived from fatty acid breakdown (beta-oxidation) and amino acid catabolism.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Metabolic effects of insulin deficiency in Type 1 Diabetes as background academic context rather than a clinical decision trigger.
Understanding that glycogenesis is blocked in T1DM explains the persistent hyperglycemia even when a patient is fasting. The body cannot store ingested or newly created glucose.
This concept is the foundation of insulin therapy. Exogenous insulin is administered to mimic the body's natural hormone, allowing glucose to be taken up by cells and stored as glycogen, thereby lowering blood sugar.
The hyperactivity of breakdown pathways (gluconeogenesis and lipolysis) explains other key features of uncontrolled T1DM: muscle wasting (from protein breakdown for gluconeogenesis) and diabetic ketoacidosis (DKA) from excessive fat breakdown.

How to Approach the Question

First, identify the core concept of the question: the function of insulin and the consequences of its absence in Type 1 Diabetes.
Recall that insulin is an anabolic hormone, meaning its primary role is to build up and store energy, particularly after a meal.
Evaluate each option based on insulin's function:
Glycogenesis is the storage of glucose. Does insulin promote this? Yes. Therefore, its absence would severely inhibit it.
Glycolysis is the use of glucose for energy. Insulin facilitates this in some tissues, but it's not purely a storage pathway.
Krebs cycle is a central energy pathway. It can use fuel from carbs, fats, or proteins. It will adapt, not stop.

Concept Tested & Keywords

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