Elsevier

Endocrine Practice

Volume 16, Issue 4, July–August 2010, Pages 600-608
Endocrine Practice

Original Article
Pilot Study to Evaluate the Effect of Short-Term Improvement in Vitamin D Status on Glucose Tolerance in Patients With Type 2 Diabetes Mellitus

https://doi.org/10.4158/EP09300.ORGet rights and content

ABSTRACT

Objective

To study the effect of improvement in vitamin D status on glucose tolerance in Asian Indian patients with moderately controlled type 2 diabetes mellitus (T2DM).

Methods

This randomized, double-blind, placebocontrolled pilot study was conducted in 28 Asian Indian patients with T2DM. Study participants were randomly assigned to a vitamin D-treated group (group D) or a placebo group (group P). Serum 25-hydroxyvitamin D, hemoglobin A1c, and serum fructosamine levels were measured, and an oral glucose tolerance test (OGTT) was performed in all patients at baseline and 4 weeks after intervention. During the OGTT, plasma glucose and serum insulin levels were measured at 0, 30, 60, 90, and 120 minutes. The unpaired t test was used to compare the groups at baseline and to compare the differences in changes from baseline to 4 weeks between the 2 study groups.

Results

Group D and group P were similar with respect to their fasting plasma glucose and serum insulin concentrations, post-OGTT plasma glucose and serum insulin levels, and hemoglobin A1c and fructosamine values at baseline. Serum 25-hydroxyvitamin D levels increased significantly in group D at 4 weeks. No significant differences were found between the groups at baseline and 4 weeks with respect to serum fructosamine, fasting plasma glucose and serum insulin, post-OGTT plasma glucose and serum insulin levels, and homeostasis model assessment of insulin resistance.

Conclusion

In this study, short-term improvement in vitamin D status was not associated with improvement in glucose tolerance, insulin secretion, or insulin sensitivity in Asian Indian patients with moderately controlled T2DM.(Endocr Pract. 2010;16:600-608)

Section snippets

INTRODUCTION

The incidence of type 2 diabetes mellitus (T2DM) is increasing alarmingly worldwide, especially in the Indian subcontinent. Despite various new antidiabetic medications, optimal management of diabetes is still an unrealized goal. Studies in animals have demonstrated a definite role for vitamin D in pancreatic beta-cell function and insulin sensitivity (1., 2., 3., 4., 5., 6., 7., 8., 9., 10.). Vitamin D insufficiency has long been suspected as a risk factor for type 1 diabetes mellitus (11).

Study Design

This randomized, double-blind, placebo-controlled pilot study was conducted in a tertiary health care center in Mumbai, India. The study was approved by the institutional ethics committee, and written informed consent was obtained from all participants.

Study Subjects

Patients with T2DM attending an outpatient clinic who fulfilled the following inclusion criteria at screening were recruited for the study:

  • 1.

    35 to 50 years of age

  • 2.

    Body mass index of 20 to 26 kg/m2

  • 3.

    Duration of diabetes mellitus < 10 years

  • 4.

RESULTS

Of the 58 patients who were screened, 28 eligible participants were recruited for the study. Eligible subjects were randomly allocated into group D (n = 14) or group P (n = 14). All patients in group D completed the study, whereas 1 patient in group P withdrew from the study after baseline investigations. A summary of the study protocol is shown in Figure 1.

DISCUSSION

We conducted a pilot study to evaluate the effect of improvement in serum 25(OH)D on glycemic status in patients with moderately controlled T2DM. In our study, despite significant improvement in serum 25(OH)D levels, no significant improvement was observed in glycemic status, insulin secretion, or insulin sensitivity. Our study was empowered to detect a change in serum fructosamine of approximately 20%. Changes in all variables, however, including serum fructosamine, fasting plasma glucose,

CONCLUSION

In this study, short-term improvement in vitamin D status did not improve glucose tolerance, insulin secretion, or insulin sensitivity in Asian Indian patients with T2DM. For confirmation of the effect of vitamin D on glycemic status, however, larger, long-term randomized controlled trials are needed.

DISCLOSURE

The authors have no multiplicity of interest to disclose.

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