Evaluation of the Internal Consistency of Measurement and Potential of a DNA-adduct as a Biomarker of Glycemic Control

Primary Objective is to replicate and validate the CEdG assay to be used in human subjects. A fully automated assay for urinary CEdG has been developed. the investigators will validate the observations made in diabetic animal models in human subjects with and without type 2 diabetes mellitus (T2DM). Specifically, the investigators will investigate and establish the inter- and intra-assay coefficients of variability in human subjects.

Secondary Objective is to determine the correlation between CEdG levels and hemoglobulin A1c (HbA1c) in human subjects with T2DM and the response to diabetic treatment and to define the relationship of CEdG with diabetic complications. The investigators will examine the relationship of CEdG with glycemic control, based on HbA1c, which is the current gold standard, in both patients with type 1 and type 2 diabetes. The investigators also compare the changes in CEdG and Hb1Ac levels in response to diabetic treatment in diabetic patients. The relationship of CEdG with diabetic complications will also be investigated in diabetic patients.

Statistical considerations for the primary objective:

Sample Size: Because there are many more variables in human subjects, the investigators calculated the sample size based on a much more conservative assumption than what the investigators observed from diabetic animal models. The investigators are planning a study of a continuous response variable from independent control and experimental subjects with 1 control per experimental subject. Based on the animal data, the investigators expect the results within each subject group to be normally distributed with a standard deviation of 0.3. If the true difference in the mean between the diabetic and non-diabetic groups is 0.5, the investigators will need to study 9 diabetic and 9 non-diabetic subjects to be able to reject the null hypothesis that the population means of the experimental and control groups are equal with probability (power) 0.9. The Type I error probability associated with this test of this null hypothesis is 0.05. To account for a possible attrition rate of 30%, the investigators will accrue 12 diabetic and 12 non-diabetic subjects to the study.

Statistical Analysis: The effect of diabetic status on urinary CEdG levels will be compared using a Student's t-test. Differences in continuous variables between the groups of subjects will be tested with either one-way ANOVA or Student's t-test when appropriate. Differences in proportions will be evaluated by a chi-square test. The continuous variables, that fail the Normality test, will be logarithmically transformed before analysis. To examine the influence of confounding variables, a stepwise regression analysis will be used. A p value less than 0.05 will be considered statistically significant.