Abstract

Objective: Bimodality in the distribution of glucose has been used to define the cut-point for the diagnosis of diabetes. Previous studies on bimodality have primarily been in populations with a high prevalence of type 2 diabetes, including one study in a white Caucasian population. All studies included participants with known diabetes. The aim of this study was to assess whether a bimodal structure is a general phenomenon in fasting- and 2-hour plasma glucose which is useful for deriving a common cut-point for diabetes in populations of different origin, both including and excluding known diabetes.

Research Design and Methods: The DETECT-2 project is an international collaboration pooling surveys from all continents. These studies include surveys where plasma glucose was measured during an OGTT, in total 43 studies (135,383 participants) from 27 countries were included. A mixture of two normal distributions was fitted to plasma glucose levels and a cut-point for normal glycaemia was estimated as their intersection. In populations with a biologically meaningful cut-point, bimodality was tested for significance.

Results: Distributions of fasting- and 2-hour plasma glucose did in general not produce bimodal structures useful for deriving cut-points for diabetes. When present, the produced cut-points were inconsistent over geographical regions.

Conclusions: Deriving cut-points for normal glycemia from distributions of fasting- and 2-hour plasma glucose does not appear to be suitable for defining diagnostic cut-points for diabetes.