Decreased insulin requirements after LAR-octreotide but not after lanreotide in an acromegalic patient.
A diabetic acromegalic man, not cured after surgery and radiosurgery, received lanreotide i.m. with great clinical and biochemical improvement. He required NPH insulin (76 to 84 units/day) to control his diabetes mellitus. Thirty-six hours after changing to LAR-octreotide (20 mg i.m/month) he presented symptomatic hypoglycemia, repeated at 48 and 72 h (50 mg/dL), despite reducing insulin to 26 Units/day. Thereafter, he reduced insulin by 30 to 50% for the first week after each LAR-octreotide injection, and gradually increased it again over the next 3 weeks. This situation persists after every injection 3 years later; this consistent behavior supports a specific effect of LAR-octreotide, and not a by chance phenomenon. No marked changes in circulating GH, IGF-1, immunoreative insulin, C-peptide, testosterone and glucose were observed prior to, and 3, 7, 14, 21, and 28 days after LAR-octreotide; however, there was 28% fall in plasma glucagon after 7 days, which rose thereafter. C-peptide (< 1.8 ng/mL) was indicative of decreased beta-cell function. To our knowledge, this is the first report of such a distinct differential behaviour of blood glucose and insulin requirements with different somatostatin analogs, and is worth recalling when starting an insulin-treated diabetic patient on this treatment. It may be related to a preferential binding of LAR-octreotide to subtype 2 somatostatin receptors in the pancreas, while lanreotide preferentially binds to subtype 5, not expressed in this tissue; this would explain the fall in glucagon, in parallel to the decrease in insulin requirements after LAR-octreotide; however, a contribution of differences in the effect of both somatostatin analogues on postreceptor signalling systems and/or intestinal carbohydrate absorption cannot be entirely ruled out.
Webb
S M
SM
Department of Endocrinology, Hospital de Sant Pau, Autonomous University of Barcelona, Spain. swebb@santpau.es
Ortega
E
E
Rodríguez-Espinosa
J
J
Mato
M E
ME
Corcoy
R
R
D000172:Acromegaly / Q000150:complications* / Q000188:drug therapy*; D003692:Delayed-Action Preparations; D048909:Diabetes Complications; D003920:Diabetes Mellitus / Q000188:drug therapy*; D004305:Dose-Response Relationship, Drug; D006728:Hormones / Q000008:administration & dosage* / Q000627:therapeutic use; D006801:Humans; D007004:Hypoglycemic Agents / Q000008:administration & dosage* / Q000627:therapeutic use; D007328:Insulin / Q000008:administration & dosage* / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D015282:Octreotide / Q000008:administration & dosage* / Q000627:therapeutic use; D010456:Peptides, Cyclic / Q000627:therapeutic use*; D013004:Somatostatin / Q000031:analogs & derivatives* / Q000627:therapeutic use*
D003692:Delayed-Action Preparations; D006728:Hormones; D007004:Hypoglycemic Agents; D007328:Insulin; D010456:Peptides, Cyclic; C060347:lanreotide; D013004:Somatostatin; D015282:Octreotide