Which condition is characterized by insufficient insulin production?

Type 1 diabetes mellitus is specifically characterized by insufficient insulin production due to the autoimmune destruction of pancreatic beta cells, which are responsible for insulin synthesis. This condition leads to an absolute deficiency of insulin, resulting in elevated blood glucose levels. Individuals with Type 1 diabetes often require exogenous insulin to manage their blood glucose levels effectively.

In contrast, Type 2 diabetes typically begins with insulin resistance and may involve varying degrees of insulin deficiency over time, but the initial problem is primarily insulin resistance rather than outright lack of production. Gestational diabetes occurs during pregnancy and is associated with insulin resistance as well, which can lead to elevated blood glucose levels but does not primarily originate from a deficiency of insulin. Metabolic syndrome encompasses a cluster of conditions that increase the risk of heart disease and diabetes, but it does not directly imply a lack of insulin production.

Thus, Type 1 diabetes is distinct in its origin of insufficient insulin production, making it the correct answer in the context of this question.