A clinical research network in diabetes for the UK

Investigation of effect on glycosylated hemoglobin, blood pressure, and body mass index of diabetes intensive education program in patients with type 2 diabetes mellitus

This study investigated the effects of a diabetes intensive education program (DIEP) on glycosylated hemoglobin (HbA(1)c), body mass index (BMI), and arterial blood pressure (BP). An 8-week randomized-controlled trial was conducted in Cumhuriyet University Hospital. Diabetes patients were randomized to control group (CG; n = 25) and intervention group (IG; n = 25) who received DIEP, including the factors affecting metabolic control and implementation of diabetes guidelines. Primary outcomes included HbA(1)c, BP, and BMI. After the 8 weeks, there was a significant decrease in HbA(1)c mean values for the intervention group. Also, BP significantly decreased from 143/87 to 130/80 mmHg in the IG as compared with an increase from 137/82 to 137/86 mmHg in the CG. In addition, the results demonstrated that DIEP improved the number of patients at goal for BP (130/80 mmHg). Baseline BMI did not change significantly in either group during the course of the study. These findings show that the DIEP may be effective in decreasing HbA(1)c levels and improving adherence to BP control.

Comparison of 11 human insulin assays: implications for clinical investigation and research

BACKGROUND

The American Diabetes Association task force on standardization of insulin assays in 1996 showed wide variation in assay bias. Newer assays are specific for insulin, with several now available on automated immunoassay analyzers.

METHODS

In 2004, we compared 11 commercially available insulin assays by analyzing 150 serum samples (99 fasting/51 postprandial) from study participants with various degrees of glucose intolerance (exclusions being type 1 diabetes, insulin treatment, or presence of insulin antibodies). All assays were calibrated against International Reference Preparation 66/304. One assay was not specific for insulin and another was an RIA; 10 assays used enzyme/chemiluminescent labels. Bland-Altman difference plots were modified to use the mean insulin from all assays on the x-axis as a common comparator.

RESULTS

As in the 1996 study, insulin values from the different assays varied by a factor of 2, with the nonspecific assay ranking in the middle of the distribution. Spearman rank correlation coefficients, for ranking samples vs the mean, were 0.983-0.997. Both offsets and concentration-dependent differences were seen in the modified difference plots. Imprecision (mean CV) for automated assays (3%) was not significantly different from manual assays (5%). Similar values were obtained when one automated assay was run in laboratories in both the UK and the US. Results of 1 assay showed lower insulin concentrations in heparinized plasma than in serum.

CONCLUSIONS

Assay performance must be considered before comparing insulin results. The 2-fold variation in insulin results may be related to specificity, manufacturers' calibration procedures or conversion factors.