Dolphins as animal models for type 2 diabetes: sustained, post-prandial hyperglycemia and hyperinsulinemia.
There is currently no known natural animal model that fully complements type 2 diabetes in humans. Criteria for a true natural animal model include the presence of a fasting hyperglycemia, evidence of insulin resistance, and pathologies matching that reported in humans. To investigate the bottlenose dolphin (Tursiops truncatus) as a comparative model for type 2 diabetes in humans, hourly plasma and urine chemistry changes, including glucose, were analyzed among five healthy, adult dolphins for 24 h following ingestion of 2.5-3.5 kg of mackerel or 2-3 L of 10% dextrose in ionosol. Fasting and 2 h post-prandial insulin levels were also determined among five adult dolphins to assess the presence of hyperinsulinemia. Finally, a case-control study compared insulin and glucagon levels among dolphins with and without iron overload, a condition associated with insulin resistance in humans. Both protein and dextrose meals caused significant increases in plasma glucose during the 0-5 h post-prandial period; dolphins fed dextrose demonstrated a sustained hyperglycemia lasting 5-10 h. Fasting plasma insulin levels among healthy dolphins mimicked those found in humans with some insulin resistance. Dolphins with hemochromatosis had higher post-prandial plasma insulin levels compared to controls. We conclude that bottlenose dolphins can demonstrate metabolic responses consistent with type 2 diabetes, specifically sustained hyperglycemia and hyperinsulinemia. Understanding more about how and why dolphins have a diabetes-like metabolism may provide new research avenues for diabetes in humans.
National Marine Mammal Foundation, San Diego, CA 92106, USA. stephanie@epitracker.com
Stephanie
S
Venn-Watson
Kevin
K
Carlin
Sam
S
Ridgway
D000818:Animals; D003924:Diabetes Mellitus, Type 2 / Q000503:physiopathology*; D004195:Disease Models, Animal; D004289:Dolphins; D005260:Female; D006943:Hyperglycemia / Q000503:physiopathology*; D006946:Hyperinsulinism / Q000503:physiopathology*; D008297:Male; D019518:Postprandial Period