The New England Journal of Medicine has published two papers that are long-term follow up studies of the original tight blood pressure and tight blood glucose studies in the United Kingdom Prospective Diabetes Study.
The study of tight blood pressure was extended as an observational study (UKPDS 81) but no attempts were made to maintain previously assigned drug therapies. Blood pressure differences noted during the randomised study had disappeared after two years with patients whose blood pressure had been tightly controlled allowed to approach those in the original control group of the study. This change led to a loss of the benefits (reduction in diabetes-related death, stroke and microvascular outcomes) observed in the original study.
This study therefore confirms the continued importance of tight blood pressure control. Adopting a less stringent approach to blood pressure management in diabetes confers little benefit in terms of reducing outcomes that are important to patients.
The study of tight blood glucose control was also extended into an observational study (UKPDS 80) and similarly no attempts were made to maintain previously assigned drug therapies. Differences were lost within a year but over the full duration of the study (up to 2002) HbA1c levels fell to below those of the original tight treatment group.
The study found differences were observed in:
- Microvascular outcomes for those patients initially treated with sulphonylurea and insulin therapy
- Myocardial infarction for patients originally treated with metformin
- Death from any cause for all patients by the end of follow up
It is notable that there is a significant drop out rate by 10 to 15 years after randomisation; the study may therefore not be sufficiently powered to detect real differences.
Action: These studies reinforce the continued importance of tight blood pressure control in patients with diabetes. Additional research may be required to assess long term importance of early and aggressive control of blood glucose especially in light of randomised trial evidence to the contrary.
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