Dr. Roberto Cesar Leite
Interview conducted by Dr. Donato Pérez García
Two decades of IPT in Brazil, international exchange, and a friendship between colleagues
Introduction
Some conversations happen out of duty, and others out of affection. This is one of the latter. For many years, Dr. Roberto Cesar Leite and I have shared more than an interest in Insulin Potentiation Therapy (IPT): we have shared classrooms, journeys, conferences and, above all, a friendship that has crossed borders.
Roberto is a physician, a specialist in Medical Nutrology, a doctor in Naturopathy and Nutrition, and coordinator of INTEGRA / SPES Centro de Ensino e Especialização em Saúde Integrada in Brazil. For close to twenty years he has been one of the leading promoters of IPT in his country.
I wanted to conduct this interview to record his journey in his own words, and also to keep, in one place, the memory of what we have lived together as colleagues and friends. What follows is our conversation.
— Dr. Donato Pérez García
The beginnings: training and integrative medicine
Dr. Donato Pérez García: Roberto, dear friend, thank you for agreeing to this conversation. Let's start at the beginning. How did your path in medicine begin?
Dr. Roberto Cesar Leite: Thank you, Donato. It is a great pleasure to do this with you. I graduated in Medicine from the Faculdade Evangélica de Medicina do Paraná in 1986. Very early on I understood that practicing medicine demands constant updating, analytical ability and a willingness to explore different therapeutic perspectives. Medicine does not end with the degree; that is where it begins.
DPG: And you did not stand still. A very broad education followed.
RCL: That's right. I expanded my training with studies in Homeopathy, Acupuncture and Medical Nutrology. In 2003 I earned a doctorate in Naturopathy and Nutrition from Bircham International University in Spain. Each stage gave me different tools to better understand human health.
DPG: What drew you to integrative medicine?
RCL: I was, and still am, interested in the relationships between metabolism, nutrition, physiological processes and complementary therapeutic approaches. Over time, that interest also led me to invest in training professionals and producing educational materials.
DPG: I have always known you as someone who thinks out loud with others, not just for himself.
RCL: I firmly believe that the evolution of medicine depends not only on accumulated experience. It depends on the ability to share knowledge, to dialogue with other professionals and to critically examine the possibilities and limitations of each approach. It was in that context that IPT began to take on an important place in my professional life.
Encountering IPT in Brazil
DPG: Let's talk about IPT. When and how did you come to it?
RCL: About twenty years ago I began working with IPT in Brazil. At that time, spreading it was a real challenge. It required dedication to studying its foundations, contact with experienced professionals and a willingness to go deeper into knowledge that was still little known among many Brazilian physicians.
DPG: What sparked your curiosity?
RCL: I wanted to understand the relationships between insulin, cellular metabolism and the hypotheses behind its use in certain therapeutic contexts. From that interest, I began devoting part of my work to studying IPT, to discussing its protocols and to seeking opportunities for Brazilian professionals to access serious information on the subject.
DPG: I remember you always insisted on knowing the history, not just the technique.
RCL: Because passing on specialized knowledge takes much more than presenting a procedure. You need to know its history, the people who contributed to its development, study its physiological foundations and critically follow the research on its safety and efficacy.
And that is where another important challenge appeared: bringing Brazilian physicians closer to international experience, creating opportunities to learn directly from those who already had years of practice. That initiative became one of the most meaningful dimensions of my journey with IPT.
Our collaboration: a bridge between Mexico and Brazil
DPG: This is where I come into the story. How do you remember the start of our collaboration?
RCL: With great affection, Donato. Among all the professional relationships I built along the way, ours holds a special place. You belong to the third generation of a family historically linked to the development and transmission of IPT. The history of the technique goes back to the work of your grandfather, Dr. Donato Pérez García, Donato I, and continued in the generations that followed. That family history is part of the story I try to preserve and share through teaching.
DPG: And you were determined to bring me to Brazil.
RCL: (Laughs) Yes, I was determined. I recognized the value of direct contact with someone who knew the evolution of IPT from the inside and had international experience. That is why I worked to bring you to Brazil to teach courses on the technique.
DPG: What did those courses mean to you?
RCL: They had a very special meaning. Besides offering learning, they brought Brazilian physicians closer to an international experience that until then had been hard for many of them to reach. Bringing a professional from abroad takes initiative, organization and the conviction that training grows stronger when different experiences are in dialogue. That was the spirit in which we did it.
DPG: And from there something more than a working relationship was born.
RCL: Exactly. Over the years our relationship went beyond the strictly professional and became a friendship built around a love of knowledge, the exchange of experiences and a dedication to teaching. For me it represents the meeting of two professionals, but also a bridge between two countries so that knowledge can flow.
DPG: For me too, Roberto. Few people understand my family's history with the respect you have shown it.
Two encounters we treasure: Austria 2012 and Curitiba 2024
DPG: There are two moments we always bring up when we see each other. The first is Austria.
RCL: Austria, 2012. It was a milestone in our journey. That meeting was captured in photographs that we later included in the IPT educational material developed at SPES. That photo is, for me, a very meaningful memory of our exchange and of the lasting ties we built around the study of the technique.
DPG: What do these international encounters give you?
RCL: They let you learn other perspectives, share experiences and better understand the historical development of a therapeutic approach. But above all, they remind me how important human relationships are in building knowledge. Medicine is an activity deeply shaped by the meeting of people. Many educational initiatives are born precisely from trust, friendship and the desire to share what we have learned.
DPG: Twelve years later we met again in your homeland.
RCL: Yes, at the 1st International Congress of Integrative Medicine Applied to Oncology, in Curitiba, November 14 to 16, 2024. The congress brought together professionals from different fields, with discussions on integrative medicine and exchange between Brazilian specialists and international guests.
Being by your side there again symbolized the continuity of our relationship. Austria and Curitiba are two different moments, but united by the same friendship, the same collaboration and the same interest in the study of IPT. That meeting was also documented in SPES's institutional material.
DPG: Why does organizing spaces like this matter so much to you?
RCL: Because they create learning environments and encourage dialogue among professionals. A congress of that size reflects a concern that has always been with me: that knowledge can be presented, discussed and subjected to critical analysis, respecting the complexity of clinical challenges.
Year &Place.What we remember
2024:Curitiba, Brazil
1st International Congress of Integrative Medicine Applied to Oncology (November 14–16)
2012: Austria
International meeting, captured in photographs in SPES educational material
Over the years: Brazil
IPT courses taught by Dr. Donato Pérez García
Science, responsibility and teaching
DPG: You have always been very clear about IPT's place in clinical practice. How would you explain it today?
RCL: IPT starts from hypotheses about the action of insulin and cellular metabolism, and proposes using it to enhance the action of certain medications in specific contexts. But the proposed mechanisms and clinical results must be analyzed according to the quality of the evidence available for each indication.
This is especially important in oncology. A practitioner's experience can help formulate questions and guide research, but on its own it does not prove efficacy or establish causality.
DPG: What do you consider essential in that debate?
RCL: Analyzing the physiological foundations, the available clinical studies, the risks associated with inducing hypoglycemia and the possible interactions between the medications used. And something I never tire of repeating: patients must be told clearly that IPT should not replace oncology treatments of established efficacy. Any use must be evaluated individually, considering the clinical situation, safety and the relevant evidence.
DPG: That honesty is one of the things I admire most about you. Tell me about SPES and your teaching work.
RCL: Through SPES Centro de Ensino e Especialização em Saúde Integrada, I have devoted myself to organizing content for professionals who want to understand the history, metabolic foundations and clinical issues of IPT. The open course on Insulin Potentiation Therapy is an extension of that work: it covers the historical evolution of the technique, the physiological hypotheses, the protocols described in the literature and what requires attention in clinical evaluation. And your participation, Donato, gives students an international perspective on the history of IPT.
DPG: What does teaching mean to you?
RCL: Sharing knowledge, yes, but also encouraging critical thinking. A responsible course should help people understand the context of a technique, examine its proposals and recognize the questions that remain open. Practitioners must be able to distinguish between clinical experience, physiological hypothesis and scientific proof.
DPG: And you also put all of that in writing.
RCL: I took part in writing the e-book “IPT — Insulin Potentiation Therapies”. It brings together the history of the technique, its physiological and metabolic foundations, the proposed mechanisms, the debates on its clinical use and the protocols described in the literature. It also covers the history of the Pérez García family and our collaboration.
The course and the book complement each other: one is training and exchange; the other, the written organization of knowledge. Both must remain open to updating and critical review, keeping pace with the scientific literature and recognizing the limits of the evidence.
Friendship, memory and legacy
DPG: Roberto, looking back, what place does our friendship hold in your story with IPT?
RCL: A special place. My journey was built not only through study and professional work, but also thanks to the people I met along the way. Our relationship brings together what I consider essential in professional life: mutual respect, a love of knowledge, collaboration and a willingness to share. Austria in 2012, the courses in Brazil and Curitiba in 2024 are moments that document that story, and they show that professional relationships can cross borders and form learning communities.
DPG: Why did you agree to be part of this testimonial project?
RCL: Because preserving the memory of these experiences has value beyond any technique. It means recording how professionals came together, how knowledge was shared and how educational initiatives were built over time. Being able to leave my story alongside those of other physicians who took part in the international history of IPT is a way of recognizing everyone who made this journey possible. I receive your invitation with deep appreciation, Donato.
DPG: How would you define the legacy you want to leave?
RCL: I do not believe a legacy is limited to titles, publications or events. It shows in the learning opportunities we help create, in the relationships we build and in the ability to pass on knowledge responsibly to the next generations. Medicine demands curiosity, intellectual humility and a willingness to revisit ideas. Experience is valuable, but it must go hand in hand with scientific research, clinical responsibility and respect for each patient.
DPG: And if you had to sum it up in one sentence?
RCL: If my path can leave a lasting contribution, I hope it will be remembered for the commitment to sharing knowledge, bringing professionals together and preserving the memory of a journey built through study, collaboration and education. And, if I may add something, also for a friendship that began in a classroom and that time has only made stronger.
DPG: Thank you, Roberto. For your generosity, your rigor and so many years of a shared path. May these pages remain as a memory of what we have built together, and as an invitation to keep doing so.
RCL: Thank you, dear friend. It has been an honor.
Dr. Roberto Cesar Leite — Physician | Specialist in Medical Nutrology | Doctor in Naturopathy and Nutrition | Coordinator of INTEGRA / SPES Centro de Ensino e Especialização em Saúde Integrada.
Interview: Dr. Donato Pérez García — October 22, 2026
