Old Drug Verapamil May Have New Use in Type 1 Diabetes

Miriam E. Tucker

February 27, 2023

In children and adolescents with new-onset type 1 diabetes, the calcium channel blocker verapamil slowed the destruction of insulin-producing pancreatic beta cells for up to a year, new data show.

Use of daily verapamil within a month of diagnosis resulted in a 30% increase in C-peptide secretion (a measure of preserved beta-cell function) compared to placebo at 52 weeks, without serious adverse events.

To put it another way, verapamil delayed the expected decline in C-peptide production from 3 months after diagnosis of type 1 diabetes to 6 months after diagnosis.

"We think this is a really, really exciting finding that's hopefully going to impact the care for children with type 1 diabetes in the new-onset period," lead author Gregory P. Forlenza, MD, said during his presentation of the data on February 24 at the annual Advanced Technologies & Treatments for Diabetes (ATTD) meeting.

"In view of the favorable safety profile, particularly by comparison with immune-suppressive agents, once-a-day oral administration, and low cost, initiation of verapamil should be a consideration for newly diagnosed patients with type 1 diabetes," added Forlenza, a pediatric endocrinologist at the Barbara Davis Center for Diabetes, Anschutz Medical Campus, University of Colorado, Aurora.

Asked to comment, Robert A. Gabbay, MD, PhD, chief scientific and medical office, American Diabetes Association, told Medscape Medical News: "This is an exciting preliminary study that suggests that an old medication, verapamil, could have benefit in those newly diagnosed with type 1 diabetes to help preserve beta-cell function and insulin production. We look forward to larger studies to verify these initial reports."

The new data were also simultaneously published in JAMA as part of the CLVer (Hybrid Closed Loop Therapy and Verapamil for Beta Cell Preservation in New Onset Type 1 Diabetes) trial.

The randomized, double-blind, six-center trial involved 113 participants, aged 7-17 years, with newly diagnosed type 1 diabetes. They were randomized to the most advanced commercially available automated insulin delivery systems available or standard care to test the effects of intensive glucose control on C-peptide levels for 52 weeks during the COVID-19 pandemic (July 2020 to September 2022). Eighty-eight patients who weighed 30 kg (66 lb) or more were further randomized (1:1) to daily extended-release verapamil or placebo for the same duration. 

The positive findings for verapamil, published in one paper, contrasted with the negative ones for the automated insulin delivery (AID) system. The latter did not prevent the expected decline in C-peptide, putting to rest a long-held hypothesis that reducing glucotoxicity might preserve beta-cell function in newly diagnosed individuals with type 1 diabetes, noted Forlenza.

Could Combination Therapy Work?

In recent years, immune-modulating agents have increasingly been shown to preserve beta-cell function in both new-onset and preclinical type 1 diabetes. One such agent, teplizumab (Tzield, Provention Bio), was approved by the US Food and Drug Administration in November 2022 to delay type 1 diabetes onset in those at high risk.

Calcium channel blockers such as verapamil — used for years to treat hypertension and cardiac arrhythmias — may accomplish the same goal as teplizumab but in a different way, by reducing the protein overexpression that induces beta-cell apoptosis and death.

Forlenza showed a slide comparing the preservation of C-peptide, which was much lower with verapamil, at 30%, than with teplizumab, at 75%.

Asked to comment, session moderator Torben Biester, MD, a pediatric diabetologist at Auf der Bult-Zentrum Diabetes-Center for Children and Adolescents, Hanover, Germany, said: "[Verapamil] is a very cheap [daily] pill. [Teplizumab] is a very high-priced...immune therapy in the US...an infusion twice for 10 days, so it's a lot more burden for the patients and a lot more risk of side effects."

"The future might be combination therapy," added Biester.

And in an editorial published in JAMA accompanying the two CLVer papers, Jennifer Couper, MD, of the University of Adelaide, Australia, agrees: "A well-tolerated, inexpensive, oral treatment such as verapamil with modest benefits on C-peptide production is relevant to practice."

The new work "supports investigation of verapamil in combination with other effective agents during the earlier stages of type 1 diabetes before insulin dependence develops," she noted.

Verapamil Results "Brilliant" but More Work Needed

In the verapamil part of the CLVer trial, by 52 weeks, verapamil doses in the youth who received it ranged from 120-360 mg/day based on weight and tolerance.

The primary outcome, C-peptide area under the curve, stayed stable, from 0.66 pmol/mL at baseline to 0.65 pmol/mL at 52 weeks in the verapamil group, compared with a drop from 0.60 pmol/mL down to 0.44 pmol/mL with placebo, a significant difference of 0.14 pmol/mL (P = .04), representing a 30% higher C-peptide level in the verapamil group.

"For us, this is a phenomenally exciting result," Forlenza commented during his presentation.

At 52 weeks, A1c was 6.6% in the verapamil group versus 6.9% with placebo, which was not significantly different. Daily insulin dose was 0.65 versus 0.74 units/kg/day, respectively, also not significantly different.

One severe hypoglycemic event occurred in each group, and one diabetic ketoacidosis event occurred in the placebo group. In the verapamil group, three participants experienced "nonserious" electrocardiogram (ECG) abnormalities and one had hypertension.

Biester said he isn't "that concerned" about the small number of mild ECG abnormalities seen in the study with verapamil, as this is a known side effect. But overall, he said, "I would think that for a recommendation for routine use it's too early after one study, even though the results are brilliant."

He noted that he is involved in a similar ongoing study of verapamil in adults with new-onset type 1 diabetes, called Ver-A-T1D.

No C-peptide Effect of Tight Glycemic Control: "A Tough Pill"

In the AID part of the study, the 113 participants were randomized 2:1 to one of two commercially available AID systems (Tandem t:slim X2 with Control-IQ or Medtronic 670G or 780G) plus frequent contact (a median of 35 times) by study staff, or standard management using a continuous glucose monitor (CGM) with an insulin pump or multiple daily injections.

At 52 weeks, A1c was 6.5% for the intensive group versus 7.1% with standard care, a significant difference. Time in blood glucose range of 70-180 mg/dL was significantly longer with intensive management, at 78%, compared with standard care, at 64%.

Nonetheless, the change in C-peptide area under the curve did not differ between the two groups, decreasing from 0.57 pmol/mL at baseline to 0.45 pmol/mL at 52 weeks with the AID system, compared with a decrease from 0.60 pmol/L down to 0.50 pmol/L with standard care (P = .89).

Forlenza commented that the hypothesis that tight glycemic control would delay the decline in C-peptide secretion "is something I think a lot of endocrinologists assumed to be true and something I've heard lots of colleagues over the years talk about."

Consequently, he said these findings are "a tough pill for us to swallow...but it's important for us in the field to understand."

"Even with frequent contacts that are well above the level we'd be able to do in standard clinical care, and even with use of the most advanced AID systems we have…we saw absolutely no difference in stimulated C-peptide levels at any of the timepoints throughout the first year or at 52 weeks."

"So, in our opinion, this," combined with a prior study from 2022, "should put this hypothesis to rest," he said.

"Excellent glycemic control has a benefit in and of itself, but it was not a successful intervention for beta-cell preservation."

Forlenza has reported serving as a consultant, speaker, or advisory board member for Medtronic, Dexcom, Abbott, Tandem Diabetes Care, Insulet, Lilly, and Beta Bionics, and his institution has also received funding on his behalf for research grants from these companies. Biester has reported receiving speaker's fees from DexCom, Medtronic, Novo Nordisk, F. Hoffmann–La Roche, Sanofi, and Ypsomed Holding; serving on advisory boards for Ascensia Diabetes Care Holdings, AstraZeneca, DexCom, and Medtronic; and receiving personal fees from SYNLAB; and is a member of the European Commission Expert Panel for Medical Devices for Endocrinology and Diabetes. Couper has reported no relevant financial relationships.

The rationale for the companion CLVer analysis of the effect of reducing glucose toxicity via tight glycemic control on C-peptide progression dates back to an inpatient study published in 1989 involving 26 adolescents using an early artificial pancreas prototype called a Biostator, in which beta-cell preservation was achieved. However, two more recent studies of this approach, including one published in late 2022, did not show a difference.

The CLVer analysis involved 113 participants randomized 2:1 to one of two commercially available AID systems (Tandem t:slim X2 with Control-IQ or Medtronic 670G or 780G) plus frequent contact by study staff, or standard management using a CGM with a pump or multiple daily injections.

Miriam E. Tucker is a freelance journalist based in the Washington, DC, area. She is a regular contributor to Medscape, with other work appearing in The Washington Post, NPR's Shots blog, and Diabetes Forecast magazine. She is on Twitter: @MiriamETucker.

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