Effect of a long-acting somatostatin analogue (BIM23014) on proliferative diabetic retinopathy: A pilot study

The present studies were undertaken to assess the mechanisms responsible for growth hormone-induced insulin resistance in man. The insulin dose-response characteristics for suppression of glucose production and stimulation of glucose utilization and their relationship to monocyte insulin binding were determined in six normal volunteers after 12-h infusion of growth hormone and 12-h infusion of saline. The infusion of growth hormone (2 micrograms . kg-1 . h-1) increased plasma growth hormone nearly threefold (to congruent to 9 ng/ml) within the range observed during sleep and exercise. This increased plasma insulin (14 +/- 1 versus 8 +/- 1 microunits/ml, P less than 0.005) concentrations without significantly altering plasma glucose concentrations or basal rates of glucose production and utilization. Insulin dose-response curves for both suppression of glucose production (half-maximal response at 37 +/- 3 versus 20 +/- 3 microunits/ml, P less than 0.01) and stimulation of glucose utilization (half-maximal response at 98 +/- 8 versus 52 +/- 8 microunits/ml, P less than 0.01) were shifted to the right with preservation of normal maximal responses to insulin. Monocyte insulin binding was unaffected. Thus, except at near maximal insulin receptor occupancy, the action of insulin on glucose production and utilization per number of monocyte insulin receptors occupied was decreased. These results indicate that increases in plasma growth hormone within the physiologic range can cause insulin resistance in man, which is due to decreases in both hepatic and extrahepatic effects of insulin. Assuming that insulin binding to monocytes reflects insulin binding in insulin sensitive tissues, this decrease in insulin action can be explained on the basis of a postreceptor defect.

We reviewed the preoperative, postoperative, and follow-up examinations, fundus photographs, and fluorescein angiograms of 175 eyes of 134 patients with proliferative diabetic retinopathy treated with panretinal photocoagulation. Forty-four (25%) of these eyes lost two or more lines of vision by the time of the last follow-up examination. Follow-ups ranged from 3 to 48 months, with a median follow-up of 15 months. The most common cause of decreased visual acuity was chronic macular edema that had developed following laser treatment, occurring in 14 (8%) eyes. The causes of visual loss following panretinal photocoagulation are discussed.