In a small study of 74 patients who’d had diabetes for a median of 30 years, 73% still had detectable C-peptide levels of as low as 3.3 pmol/L after a meal, Richard Oram, MD, of Exeter University in England, and colleagues reported online in Diabetologia. (C-peptide is a byproduct when insulin is produced.)

”Historically, people with type 1 diabetes were thought to progress to total insulin deficiency, but we’ve shown that’s not the case,” Oram told MedPage Today. ”Most [patients] with even long-standing type 1 diabetes still make tiny amounts of insulin.”

Oram said the study raises questions about whether tiny residual levels make a clinical difference — with regard to complication and hypoglycemia rates, for example — and whether these remaining cells could regenerate. Also, he said, studying the differences between those who continue to produce minimal amounts of insulin and those who don’t may contribute to a better understanding of the biology of type 1 diabetes.

Jay Skyler, MD, of the University of Miami, who was not involved in the study, told MedPage Today it’s an ”important data point to have because it indicates that about 75% of people have demonstrable function of some kind and that may be worth paying attention to.”

However, he said it’s ”so low we have no idea if it’s of any significance clinically,” noting that there are no therapies that restore beta cell function at the previously lowest detectable levels.

”There is potential for [beta cells] to be reactivated, but we need to figure out what therapies we can use to awaken them,” Skyler said.

Previous assays have had a C-peptide detection limit of 30 pmol/L but newer ultrasensitive assays can detect levels under 5 pmol/L.

To assess what those assays could reveal in patients with long-standing type 1 diabetes, Oram and colleagues ran the tests in 74 patients who’d had the disease for a median duration of 30 years, and who had been diagnosed at a median age of 16.

They measured fasting and stimulated C-peptide levels using a Roche device that had a reported limit of detection of 3.3 pmol/L

They found that post-stimulation serum C-peptide was detectable at very low levels (below 3.3 pmol/L) in 73% of patients when measured 90 minutes after a mixed meal — far higher than the 35% who had detectable levels when using a cutoff of 30 pmol/L at that time, they reported.

The median C-peptide rose from fasting levels of 12 pmol/L to 23 pmol/L 90 minutes after a mixed meal (P<0.0001).

In all patients with detectable levels, C-peptide either increased (80%) or stayed the same in response to a meal, with no indication of levels falling (P<0.0001).

Oram and colleagues concluded that most patients with a long duration of type 1 diabetes continue to secrete very low levels of endogenousinsulin, which still rise in response to a meal — suggesting that some beta cells are either escaping immune attack or undergoing regeneration.

Oram said the next step is to conduct a larger study ”to look at the genetics and immune systems of people still making insulin, and to answer the important question of whether the complications of type 1 diabetes are reduced in people with low levels of insulin.”

From www.medpagetoday.com

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