The objective of this study was to evaluate the metabolic effects and opthalmologic effects of
alpha-interferon therapy in
diabetes mellitus patients with proliferative
diabetic retinopathy (PDR). Three volunteer patients [
insulin-dependent diabetes mellitus (
IDDM),
insulin requiring
non-insulin-dependent diabetes mellitus (
NIDDM), and
maturity onset diabetes of the young (
MODY)] threatened with
blindness due to progressive PDR were treated with
alpha interferon for 4 months and were evaluated at intervals of 1-2 weeks to monitor the
drug effects on
carbohydrate tolerance and possible beneficial
therapeutic effects on the preexisting PDR. Metabolic studies included basal and postsustacal
glucose,
c-peptide and
glucagon, fasting serum
cortisol,
free fatty acids,
growth hormone,
insulin-like growth factor-1, and urinary microalbumin excretion. Ophthalmologic studies included visual acuity,
slit lamp examination, gonioscopy,
fluorescein angiography, and standard colored fundus photographs. In all subjects,
hyperglycemia worsened with duration of increasing dosage of
interferon therapy, requiring progressively higher daily
insulin requirements of 17%-68% above pretreatment values. Lowered levels of stimulated
C-peptide were observed in the
NIDDM and
MODY subjects. The counterregulatory
hormones (
cortisol,
growth hormone, and
glucagon) were elevated during the 4 months of
interferon therapy. In all subjects, visual acuity appeared to stabilize. No new
retinal hemorrhages occurred during the 4 months of
interferon administration, although all subjects experienced
hemorrhage within 6 weeks of termination of the
drug. Although only three subjects were investigated, the 1-2 week frequency of metabolic and opthalmologic studies permit some conclusions. The metabolic effects of
alpha interferon in our diabetic subjects were consistent worsening of
carbohydrate tolerance associated with impaired beta-cell secretion and increased
insulin resistance. The extensive opthalmologic investigation suggested protection from
retinal hemorrhage while receiving
interferon, but further studies are indicated to validate these proposed and antiangiogenic properties.