Which effect is most likely to result from treatment with metformin in a patient with type 2 diabetes?

Metformin is primarily known for its ability to inhibit hepatic gluconeogenesis, which is the process by which the liver produces glucose from non-carbohydrate sources. In patients with type 2 diabetes, liver glucose production can be excessively high, contributing to hyperglycemia. By reducing this output, metformin helps lower overall blood sugar levels, making it a cornerstone of diabetes management.

Furthermore, metformin enhances insulin sensitivity in peripheral tissues, which aids in better glucose utilization by the muscles and fat cells. However, its most prominent and direct effect is on the liver, where it acts to decrease the production of glucose, addressing one of the primary issues in type 2 diabetes. This helps control blood sugar levels and can lead to improvements in metabolic parameters for the patient.

While the other options mention potential effects related to insulin secretion, carbohydrate digestion, and fat deposition, they are either inaccurate regarding the primary actions of metformin or do not represent its most significant effect. Thus, inhibiting hepatic gluconeogenesis correctly identifies the primary action of metformin in the treatment of type 2 diabetes.