Mechanism Underlying Beta-cell Failure in Obese African Americans With History of Hyperglycemic Crises

Overview

Obesity is common in African American (AA) patients with newly diagnosed diabetes who present with diabetic ketoacidosis (DKA). Despite the presentation with severe symptoms of insulinopenia and ketoacidosis, clinical and immunogenetic observations indicate that most obese AA patients with DKA have type 2 diabetes. In such patients, previous studies reveal that: a) at presentation, obese AA patients with DKA have markedly decreased pancreatic insulin secretion, lower than in obese non-DKA patients admitted with comparable hyperglycemia, but significantly greater than in lean patients with DKA; b) aggressive diabetic management results in significant improvement in beta-cell function and insulin sensitivity sufficient to allow discontinuation of insulin therapy within 3 months of follow-up. Based on these observations the researchers conclude that similar to obese patients with hyperglycemia, most obese AA with DKA have type 2 diabetes, and that although defects in both insulin secretion and insulin action are present, transient b-cell failure is the primary defect in the development of ketoacidosis.

Obese AA patients with a history of DKA who later experience near-normoglycemia remission represent an ideal population in which to define the sequence of events that lead to b-cell dysfunction in type 2 diabetes. The researchers hypothesize that obese AA with DKA will prove particularly susceptible to beta-cells dysfunction due to sustained elevations of plasma glucose (glucose toxicity) and/or free fatty acid levels (lipotoxicity). This study will test beta-cell response by administering a glucose infusion to diabetic African Americans with a history of DKA, diabetic African Americans without a history of DKA, and non-diabetic African Americans.