Patterns of Metabolic Progression to Type 1 Diabetes in the Diabetes Prevention Trial-Type 1

Columbia University, New York, New York, United States
Diabetes Care (Impact Factor: 8.42). 04/2006; 29(3):643-9. DOI: 10.2337/diacare.29.03.06.dc05-1006
Source: PubMed


There is little information regarding the pattern of metabolic deterioration before the onset of type 1 diabetes. The goal of this study was to utilize data from the Diabetes Prevention Trial-Type 1 (DPT-1) to obtain a picture of the metabolic progression to type 1 diabetes over a period of approximately 2.5 years before its diagnosis.
Fifty-four DPT-1 participants (22 in the parenteral trial and 32 in the oral trial) were studied. All had oral glucose tolerance tests (OGTTs) at 6-month intervals from approximately 30 to 6 months before diagnosis. The vast majority also had OGTTs at diagnosis. Changes in OGTT glucose and C-peptide indexes from 30 to 6 months before diagnosis were examined by calculating slopes of the indexes for each individual over that time period. Changes from 6 months before diagnosis to diagnosis were examined by paired comparisons of the OGTT metabolic indexes between the time points.
Glucose levels increased gradually from 30 to 6 months before diagnosis in both the parenteral and oral groups (P < 0.001 for all indexes). Area under the curve (AUC) C-peptide (P < 0.05) and AUC C-peptide-to-AUC glucose ratio (P < 0.001) values decreased in the oral group; peak C-peptide-to-2-h glucose ratio values decreased in both groups (P < 0.001). In participants who also had OGTTs at diagnosis, AUC C-peptide (parenteral group, P < 0.05) and peak C-peptide (oral group, P < 0.05) values decreased from the last 6 months before diagnosis; stimulated C-peptide-to-glucose ratio values decreased in both groups (P < 0.001). Conversely, fasting C-peptide levels increased in both groups (oral group, P < 0.01). Fasting C-peptide-to-fasting glucose ratio values remained constant throughout the 30-month follow-up.
These data indicate that over a period of at least 2 years, glucose tolerance gradually deteriorates as stimulated C-peptide levels slowly decline in a substantial number of individuals who develop type 1 diabetes. However, fasting C-peptide levels are maintained, even at diagnosis.

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Available from: David D Cuthbertson, Aug 31, 2015
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    • "Studies by Tsai et al. (2006) and Sosenko et al. (2008), using data from the DPT-1 effort have identified a progressive decline in C-peptide responses that are relatively modest during the prediabetic period compared with the changes after diagnosis with hyperglycemia. Interpretation of the changes in C-peptide responses may be more complicated in children because there is an age-related increase in C-peptide levels and therefore, the absence of an increase may be equivalent to a decline in response (Sosenko et al. 2006, 2008; Tsai et al. 2006). After the onset of disease, the decline over time appears to be more dramatic. "
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