Table 3: Associations of VDR polymorphisms with insulin secretion, insulin resistance, and T2DM. VDR: vitamin D receptor; T2DM: type 2 diabetes mellitus; OGTT: oral glucose tolerance test; HDL-C: high density lipoprotein cholesterol; HOMA-IR: homeostasis model assessment of insulin resistance; AUC: area under the curve; WHR, waist-to-hip ratio; HOMA- : homeostasis model assessment of -cell function; LDL-C: low density lipoprotein cholesterol; OR: odds ratio; HbA1c: glycosylated hemoglobin.

Author, year (ref)Subject CharacteristicsVDR gene investigatedMeasurement of insulin metabolismMain outcomeNotes

(a) Insulin Secretion

Speer et al. [78] 200149 Caucasians with T2DM, 29 subjects with obesity but no T2DM, 138 healthy controlsBsmIFasting and postprandial C-peptideHigher postprandial C-peptide in BB genotype among T2DM and obese subjectsHighest postprandial C-peptide in subjects with BB and estrogen receptor polymorphism
Hitman et al. 1998 [79]171 Bangladeshi AsiansTaqI, BsmI, ApaIOGTTHigher insulin secretion index in AA genotype No genotype differences in 32, 33 split proinsulin
Ogunkolade et al. 2002 [80]143 healthy Bangladeshi AsiansTaqI, BsmI, Fokl, ApaIOGTTTaqI genotype independently predicted insulin secretion index; tt genotypes had greatest insulin secretion index

(b) Insulin resistance

Filus et al. 2008 [81]176 Polish menFokl, BsmIFasting insulin  and glucoseFF/Ff genotype associated with greater fasting insulin than ffBB genotype associated with greater BMI  and waist circumference; FF genotype associated with lower HDL-C
Chiu et al. 2001 [82]49 glucose-tolerant Caucasian AmericansFokIFasting insulin  and glucoseff/Ff genotypes had higher fasting insulin and HOMA-IR than FF; FokI genotype independently predicted HOMA-IRff/Ff genotypes had higher postchallenge insulin AUC; higher WHR in ff/Ff genotypes; HOMA- did not differ between genotypes
Oh and Barret-Connor 2002 [83]1545 Caucasian AmericansTaqI, BsmI, ApaIFasting insulin  and glucoseFasting glucose higher in aa genotype (ApaI); HOMA-IR higher in BB genotype (BsmI) Trend towards higher aa frequency in subjects with T2DM versus those without ( )
Ortlepp et al. 2003 [84]1539 healthy, male German soldiersBsmIFasting glucoseFasting glucose independently associated with BsmI VDR (BB genotype) only in subjects with low physical activity
Tworowska-Bardińska et al. 2008 [85]350 healthy, Polish postmenopausal womenBsmIFasting insulin  and glucoseNo difference in fasting insulin, glucose, or fasting insulin resistance index between genotypesGreater LDL-C in BB genotype among those with central obesity

(c) Type 2 Diabetes

Ortlepp et al. 2003 [84]293 German adults at risk for coronary artery diseaseBsmIHigher T2DM prevalence in BB versus bb genotype; OR of 3.64 (CI: 1.53–8.55)Higher coronary artery disease prevalence in BB genotype
Dilmec et al. 2009 [86]72 Turkish adults with T2DM versus 169 healthy controlsTaqI, ApaINo statistical difference in genotype frequencies among cases versus controlsNo difference in fasting plasma glucose or HbA1c among subjects with VDR polymorphisms versus those without
Malecki et al. 2003 [87]308 Polish adults with T2DM versus 240 controlsTaqI, BsmI, Fokl, ApaINo statistical difference in genotype frequencies among cases versus controls
Ye 2001 et al. [88]309 Caucasians (French) with T2DM versus 143 controlsTaqI, BsmI, Tru9I, ApaINo statistical difference in genotype frequencies among cases versus controlsTT (TaqI) and bb (BsmI) genotypes associated with BMI among subjects with early onset T2DM
Boullu-Sanchis et al. 1999 [89]89 migrant Indians of Guadeloupe with T2DM versus 100 controlsTaqI, ApaINo statistical difference in genotype frequencies among cases versus controls