In summary, the microvascular benefits were not promising
There were no significant differences between the two study groups in the number of new eye procedures.
- The cumulative rates of events in all patients, including those who had undergone eye procedures at baseline, did not differ significantly.
- Fundus photographs showed no significant differences in progression to proliferative diabetic retinopathy (P=0.27) or in progression to clinically important macular edema (P=0.31).
- There was a nonsignificant trend toward a beneficial effect in the intensive-therapy group with respect to diabetic retinopathy, with an increased incidence of at least two steps in severity in the standard-therapy group (P=0.07).
- The between-group difference in new onset of retinopathy was not significant (P=0.27)
- Severe renal changes were unaffected by treatment (P=0.35).
- Any worsening of albumin excretion was greater in the standard-therapy group (P=0.05).
Since Andy did such a great job of hitting all of the main points, I will just raise some questions I had when reading it...perhaps you guys can enlighten me about some of them:
- The study reports that a sample size of 1700 patients provided a power of 86% to detect a relative difference of 21% in primary outcome. --> is 86% sufficient or underpowered?
- Mean duration of diabetes was 11.5 years and 40% of subjects had already had a cardiovascular event. --> if almost half of the subjects already have a CV event, isn’t the study now have two additional groups, those with CV disease and those without. Should these groups be studied separately?
- The lack of difference in microvascular disease was also very surprising because of the amount of data available to show that tight control dramatically improves this.
- Overall, my big criticism is the inclusion of the subjects with and without CV disease into one large group. This really is an issue of primary prevention vs. secondary prevention and the groups don't belong together. Without this combined group the study is under-powered to detect a difference. They found a slight decrease in the primary outcome in intense therapy vs. standard and I really think with adequate power, this difference is statistically significant.