Blood glucose and diabetic retinopathy: a critical appraisal of new evidence.

The relationship between blood glucose and diabetic retinopathy remains controversial. To obtain a proper perspective on this issue, a critical appraisal of clinical evidence published between 1974 and 1984 was done using standard methodologic criteria. Thirteen cohort studies and four intervention trials were found which provided the following new information: systolic hypertension, alcohol ingestion, female sex, and obesity were implicated as potential adverse prognostic factors related to retinopathy development. Although initial diagnostic blood glucose concentration was associated with subsequent retinopathy development, the reviewed studies did not provide evidence that tight glucose control prevented or retarded its development and progression. Some funduscopic and angiographic lesions deteriorated with tight control.