From the Guidelines
The correct answer is C. Decreased, due to lack of insulin-mediated activation of glycogen synthase. When a patient with type 1 diabetes skips their insulin injection after consuming a carbohydrate-rich meal, glycogenesis in the liver will be significantly decreased. This occurs because insulin is essential for activating glycogen synthase, the key enzyme that catalyzes glycogen formation from glucose. Without insulin, glucose cannot be efficiently taken up by liver cells, and the glycogen synthase enzyme remains in its inactive form. As a result, the liver cannot convert the elevated blood glucose into glycogen for storage. Instead, blood glucose levels will continue to rise, potentially leading to hyperglycemia and, if prolonged, ketoacidosis. This scenario highlights the critical role of insulin in glucose metabolism and storage, particularly after carbohydrate consumption when the body needs to clear excess glucose from the bloodstream, as supported by the most recent guidelines on diabetes management 1.
Some key points to consider in the management of type 1 diabetes include:
- Learning how to count carbohydrates or use another meal planning approach to quantify carbohydrate intake, as outlined in the nutrition therapy recommendations for the management of adults with diabetes 1.
- Taking mealtime insulin before eating, and adjusting the dose based on the amount of carbohydrates consumed, to match the mealtime insulin to the carbohydrates consumed 1.
- Avoiding skipping meals to reduce the risk of hypoglycemia, especially when taking premixed insulin or a fixed insulin plan 1.
- Being aware of the potential risks of hyperglycemia and ketoacidosis if insulin injections are skipped, and taking steps to prevent these complications, such as monitoring blood glucose levels closely and adjusting insulin doses as needed 1.
Overall, the management of type 1 diabetes requires careful attention to carbohydrate intake, insulin dosing, and blood glucose monitoring to prevent complications and maintain good glycemic control, as emphasized in the recent standards of care in diabetes 1.
From the Research
Effect of Skipping Insulin Injection on Glycogenesis in the Liver
- Skipping an insulin injection after a carbohydrate-rich meal would lead to elevated glucose levels in the blood, as insulin is necessary for glucose uptake by cells 2.
- Insulin plays a crucial role in stimulating glycogen synthesis in the liver by promoting a net decrease in the extent of phosphorylation of glycogen synthase, the rate-limiting enzyme in the pathway of glycogen synthesis 3.
- Without insulin, glycogen synthase is not activated, leading to a decrease in glycogen synthesis in the liver.
- The correct answer is:
- C. Decreased, due to lack of insulin-mediated activation of glycogen synthase
Mechanism of Insulin-Mediated Glycogen Synthesis
- Insulin stimulates glycogen synthesis by increasing the activity of glycogen synthase, which is achieved by promoting its dephosphorylation 3.
- The dephosphorylation of glycogen synthase increases its activity, allowing for the synthesis of glycogen in the liver.
- Insulin's ability to stimulate glycogen synthesis is critical for maintaining normal glucose homeostasis, especially after a carbohydrate-rich meal 2.
Consequences of Elevated Glucose Levels
- Elevated glucose levels in the blood can lead to various complications, including hyperglycemia, which can cause damage to organs and tissues over time 4, 5.
- The absence of insulin-mediated glycogen synthesis in the liver can exacerbate hyperglycemia, leading to further complications.
- It is essential to maintain proper insulin therapy to prevent hyperglycemia and ensure normal glucose homeostasis 6.