Final answer:
Inadequate secretion of insulin leads to an increase in blood sugar levels.
Step-by-step explanation:
Insulin is a hormone that is secreted by the pancreas in response to high blood glucose levels. Its main function is to facilitate the uptake of glucose from the blood into cells, where it can be used for energy or stored as glycogen. However, in cases where there is inadequate secretion of insulin, such as in individuals with type 1 diabetes, blood sugar levels increase because glucose cannot enter cells effectively.