Table 3.
Model | Treatments | Primary Outcomes |
---|---|---|
Cell/Cell Culture Studies | ||
β-cell lines | 1,25D | Improved maintenance of normal cell function with cytokines [19] Increased β-cell proliferation [22] Reduced ER stress and apoptosis in the presence of H2O2 [23] Effects on cell survival unclear: pro-survival [19,24], no effect [20] |
Isolated rat β-cells | 1,25D | Reduced cytokine overexpression, no change cellular apoptosis when treated with cytokines [20] Improved islet insulin release [28] |
Human islets | 1,25D | Reduced apoptosis [19,27] |
Human IPS β-like cells | Calcipotriol | Reduced apoptosis in presence of IL-1β [17] |
Animal Studies | ||
NOD mice | Analogues | Improved β-cell survival and decreased insulitis [30] Reduced incidence of T1D and improved pancreatic insulin [20,31,32] Decreased progression to T1D (mice lacking Ins2 gene) [32] Improved efficacy of islet transplants and delayed recurrence of autoimmune diabetes [33] |
1,25D | Reduced incidence of T1D and improved pancreatic insulin [31] | |
VDR mice | Transgenic | Preservation of β-cell mass following STZ [35] |
Null | Develop hypocalcaemia and β-cell dysfunction [37] which is ameliorated by rescue diet (high calcium, lactulose, phosphate) [38] | |
C57Bl/6 mice | 1,25D | Improved blood glucose and serum insulin when treated with low-dose STZ [24] |
Diabetic Wistar rats | Vitamin D | Improved β-cell function and HbA1c [36] |
Human Studies | ||
Early life | Supplementation with vitamin D | Reduced risk of T1D development intake of vitamin D and risk of type 1 diabetes: a birth-cohort study [55,59] Conflicting evidence regarding increased maternal vitamin D intake (pro No effect of the 1alpha,25-dihydroxyvitamin D3 on beta-cell residual function and insulin requirement in adults vs. no effect [58] |
Recent onset T1D | 25D | Beneficial effects on C-peptide levels over time (trend to slower decrease in C-peptide [62], if not elevated C-peptide levels [66] |
Analogues | Lower insulin dose and enhanced C-peptide (boys only) [68] | |
Recent onset T1D | 1,25D | Lower insulin requirements at 3 and 6 months [64] |
25D | Enhanced/higher C-peptide levels [65,73,74] Lower insulin requirements [67] Improved HbA1c [73] |
|
Analogues | Slower decline in HbA1c levels over time [69] | |
Human Studies (Negative/Null Findings) | ||
Recent onset T1D | Combined Rx + D | Study in children. No beneficial effects [63] |
Recent onset T1D | 1,25D | No effects on β-cell function [60,71,72] |