RETINAL OXYGEN-CONSUMPTION DURING HYPERGLYCEMIA IN PATIENTS WITH DIABETES WITHOUT RETINOPATHY

Objective: This study aimed to determine whether retinal oxygen consum ption in patients with diabetes without retinopathy is affected by acu te changes in blood glucose. Design: The study design was a nonrandomi zed, interventional clinical study. Participants: The study consisted of 12 patients with diabetes without ophthalmoscopically visible diabe tic retinopathy whose ages were 20 to 59 years (mean, 33.7 years). Int ervention: Retinal vessel oximetry was performed on subjects during no rmoglycemia and during acutely induced hyperglycemia. Hyperglycemia wa s achieved with the ingestion of an oral glucose load, Main Outcome Me asures: Changes in retinal arterial and venous blood oxygen saturation resulting from systemic blood glucose changes were measured. Measurem ents were made using a noninvasive, two-wavelength digital imaging ret inal vessel oximeter. Results: In each subject, the measured retinal v enous blood oxygen saturation decreased significantly during hyperglyc emia. The amount of decrease in venous oxygen saturation associated wi th hyperglycemia was positively correlated with the duration of diabet es. The measured retinal arterial oxygen saturation did not change sig nificantly during hyperglycemia, Conclusions: These results, taken wit h the observations of numerous other investigators that show increased blood flow during acute hyperglycemia, provide evidence of substantia lly increased retinal oxygen consumption during hyperglycemia. The res ults also complement previous observations of the effect of diabetes o n retinal autoregulation.