A Blind, Fat Fish Yields Diabetes Clues: Medicine’s Next Big Thing?


BOSTON, Mass. (Ivanhoe Newswire) — When it comes to diabetes, diet, exercise and medication can help some people avoid dangerous complications, but experts say there’s still a lot to learn. Now researchers at Harvard Medical School are looking in a very unlikely place to improve human health.

Tanks upon tanks of ordinary looking lab fish. But when you get closer …

“The cave fish has no pigment, so they’re this whitish fish, with no eyes at all,” said Misty Riddle, PhD, a Biologist at Harvard Medical School. (Read Full Interview)

After millions of years swimming in dark caverns, this Mexican tetra evolved without orbs.  For Harvard evolutionary and developmental biologist Misty Riddle, it’s not the strange outside that’s fascinating. It’s what’s inside.

Riddle explained, “If you dissect this fish, and even just looking at them they seem to store fat everywhere. We wondered what other type of metabolic changes there would be.”

Riddle found these cavefish had huge swings in blood glucose levels, much like people with type two diabetes. People with type two diabetes also have insulin resistance. Over time, high blood glucose levels and insulin resistance can lead to diabetes in people and serious complications.

Bhavna Desai, PhD a Postdoctoral Scientist in endocrinology and metabolism, BIDMC, at Harvard Medical School told Ivanhoe, “Vascular damage causes heart disease and causes liver damage. Diabetic kidney disease.”

Despite the abnormal blood glucose levels, the cavefish have none of the health side effects. Researchers say understanding why the fish don’t develop complications could help them find a pathway for new drugs.

Riddle stated, “If we can learn about how that’s different maybe we can apply that to humans.”

Mysteries of the Mexican caves that could help an American health epidemic.

Riddle says the cavefish in her lab have normal life expectancies, despite having high glucose levels and insulin resistance.  Many of the fish have been in the lab for up to 15 years.


Contributors to this news report include: Cyndy McGrath, Field and Supervising Producer; Hayley Hudson, Assistant Producer; Roque Correa, Videographer and Editor.


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REPORT:    MB #4453


BACKGROUND: Diabetes mellitus refers to a group of diseases that affect how your body uses blood sugar (glucose). Glucose is vital to your health because it’s an important source of energy for the cells that make up your muscles and tissues. It’s also your brain’s main source of fuel. The underlying cause of diabetes varies by type, but no matter what type of diabetes you have, it can lead to excess sugar in your blood. Too much sugar in your blood can lead to serious health problems. Chronic diabetes conditions include type 1 diabetes and type 2 diabetes. Potentially reversible diabetes conditions include prediabetes, when your blood sugar levels are higher than normal, but not high enough to be classified as diabetes, and gestational diabetes, which occurs during pregnancy but may resolve after the baby is delivered.

(Source: https://www.mayoclinic.org/diseases-conditions/diabetes/symptoms-causes/syc-20371444)


DIAGNOSING: There are several tests to test for diabetes. The Glycated hemoglobin (A1C) test, which doesn’t require fasting, indicates your average blood sugar level for the past two to three months. It measures the percentage of blood sugar attached to hemoglobin, the oxygen-carrying protein in red blood cells. If the A1C test results aren’t consistent, the test isn’t available, or you have certain conditions that can make the A1C test inaccurate, such as if you’re pregnant or have an uncommon form of hemoglobin, your doctor may use the following tests to diagnose diabetes: a random sugar blood test, a fasting sugar blood test, or an oral glucose tolerance test.

(Source: https://www.mayoclinic.org/diseases-conditions/diabetes/diagnosis-treatment/drc-20371451)


NEW RESEARCH: Misty Riddle, PhD, Post-Doctoral Fellow and Evolutionary Developmental Biologist is studying cave fish and how they can relate to diabetes in humans. Riddle said, “If you dissect these fish or even just looking at them they seem to store fat everywhere. We wondered what other type of metabolic changes there would be. We know in humans sometimes obesity is associated with dysregulation of glucose homeostasis, and so that’s one thing we decided to study, what does their blood glucose regulation look like.” She hopes to find answers with these fish, “we found that there was a mutation in insulin receptor in these fish. And what was surprising was they had a mutation that was the same mutation found in some humans that have this really rare form of insulin resistance that’s really deadly. If we can learn about how that’s different maybe we could apply that to humans or understanding why humans with the mutation have these detrimental effects that the fish avoid.”

(Source: Misty Riddle, PhD)


Ekaterina Pesheva, PR



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Doctor Q and A

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