Vitamin D, Parathyroid Hormone, and Parathyroid Hormone-Related Peptide Interaction in Diabetes Mellitus

Introduction

The prevalence of diabetes mellitus (DM) is increasing all over the world.¹ The number of cases is expected to increase from 171 million in 2000 to 366 million in 2030.² According to the latest data from the 2011 National DM Fact Sheet,³ in the United States, 25.8 million children and adults (8.3% of the US population) have DM. In 2004, DM was considered to be the cause of 44% of new cases of kidney failure in the United States and to be the leading cause for kidney failure. It is also considered the leading cause of new cases of blindness in adults aged 20–74 years. The estimated DM cost in the United States in 2007 was $174 billion.³ The tremendous increase in the prevalence of DM has been linked to multiple factors, which include the obesity epidemic, sedentary lifestyle, population aging, diabetes awareness, early diagnosis, and environmental factors. Several observational studies have linked hypovitaminosis D with the incidence of DM.^4–7

Abstract

Introduction

Diabetes mellitus (DM) and hypovitaminosis D are among the most common endocrine disorders. The prevalence of DM and hypovitaminosis D are increasing all over the world. Observational studies suggest that hypovitaminosis D is a risk factor for several multifactorial diseases including type I and II DM. Parathyroid hormone (PTH)-related peptide (PTHrP) is a paracrine factor that increases pancreatic beta cells’ proliferation and improves insulin secretion. Different studies have shown that diabetic patients with hypovitaminosis D have low or inappropriately normal serum levels of PTH but high PTHrP.

Objectives

How these hormones regulate each other in diabetic patients has not been fully understood. This review discusses possible explanations and hypotheses based on experimental and human studies.

Methods

PubMed was used as the search tool for this article, using the following keywords: beta cells; diabetes; 1,25(OH)2D3; parathyroid hormone; parathyroid hormone-related peptide; parathyroid hormone-related protein; vitamin D.

Results

Vitamin D and PTHrP can act in cooperation with each other to play major roles in blood sugar control.

Conclusion

The explanations and hypotheses reviewed here can be starting points toward understanding the role of vitamin D, PTH, and PTHrP in the pathogenesis of DM. PTHrP plays a promising role as a potential drug for type II DM.

Keywords

beta cells, diabetes, 1,25(OH)2D3, parathyroid hormone, parathyroid hormone-related peptide, parathyroid hormone-related protein, vitamin D