Maintenance of normal blood glucose levels depends on a complex interplay between
the insulin responsiveness of skeletal muscle and liver and glucose-stimulated
insulin secretion by pancreatic b cells. Defects in the former are responsible for insulin
resistance, and defects in the latter are responsible for progression to hyperglycemia.
Emerging evidence supports the potentially unifying hypothesis that both of these
prominent features of type 2 diabetes are caused by mitochondrial dysfunction.
Type 2 diabetes is the most common metabolic disease in the world. In the United States,
it is the leading cause of blindness, end-stage renal disease, and nontraumatic loss of limb,
with associated health care costs estimated to exceed $130 billion per year (1). Of even
greater concern, type 2 diabetes is rapidly becoming a global pandemic and is projected
to afflict more than 300 million individuals worldwide by the year 2025, with most of
the increase occurring in India and Asia (2). Although the primary cause of this disease
unknown, it is clear that insulin resistance plays an early role in its pathogenesis and
that defects in insulin secretion by pancreatic b cells are instrumental in the progression to
hyperglycemia. Here, we explore the potentially unifying hypothesis that these two prominent
features of type 2 diabetes are both attributable to defects in mitochondria, the organelles
that provide energy to the cell.
Role of Intracellular Fatty Acid
Metabolites in Insulin Resistance
Several lines of evidence indicate that insulin resistance is an early feature of type 2
diabetes. First, virtually all patients with type 2 diabetes are insulin-resistant, and prospective
studies have shown that this insulinresistant state develops 1 to 2 decades before
the onset of the disease (3–5). Second, insulin resistance in the offspring of parents
with type 2 diabetes is the best predictor for later development of the disease . Lastly,
perturbations that reduce insulin resistance prevent the development of diabetes .