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-β: homeostasis model assessment of β-cell function; LDL-C: low density lipoprotein cholesterol; OR: odds ratio; HbA1c: glycosylated hemoglobin.

Author, year (ref)	Subject Characteristics	VDR gene investigated	Measurement of insulin metabolism	Main outcome	Notes
(a) Insulin Secretion
Speer et al. [78] 2001	49 Caucasians with T2DM, 29 subjects with obesity but no T2DM, 138 healthy controls	BsmI	Fasting and postprandial C-peptide	Higher postprandial C-peptide in BB genotype among T2DM and obese subjects	Highest postprandial C-peptide in subjects with BB and estrogen receptor polymorphism
Hitman et al. 1998 [79]	171 Bangladeshi Asians	TaqI, BsmI, ApaI	OGTT	Higher insulin secretion index in AA genotype	No genotype differences in 32, 33 split proinsulin
Ogunkolade et al. 2002 [80]	143 healthy Bangladeshi Asians	TaqI, BsmI, Fokl, ApaI	OGTT	TaqI genotype independently predicted insulin secretion index; tt genotypes had greatest insulin secretion index	—
(b) Insulin resistance
Filus et al. 2008 [81]	176 Polish men	Fokl, BsmI	Fasting insulin and glucose	FF/Ff genotype associated with greater fasting insulin than ff	BB genotype associated with greater BMI and waist circumference; FF genotype associated with lower HDL-C
Chiu et al. 2001 [82]	49 glucose-tolerant Caucasian Americans	FokI	Fasting insulin and glucose	ff/Ff genotypes had higher fasting insulin and HOMA-IR than FF; FokI genotype independently predicted HOMA-IR	ff/Ff genotypes had higher postchallenge insulin AUC; higher WHR in ff/Ff genotypes; HOMA-β did not differ between genotypes
Oh and Barret-Connor 2002 [83]	1545 Caucasian Americans	TaqI, BsmI, ApaI	Fasting insulin and glucose	Fasting 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 (P = .058)
Ortlepp et al. 2003 [84]	1539 healthy, male German soldiers	BsmI	Fasting glucose	Fasting 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 women	BsmI	Fasting insulin and glucose	No difference in fasting insulin, glucose, or fasting insulin resistance index between genotypes	Greater 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 disease	BsmI	—	Higher 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 controls	TaqI, ApaI	—	No statistical difference in genotype frequencies among cases versus controls	No 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 controls	TaqI, BsmI, Fokl, ApaI	—	No statistical difference in genotype frequencies among cases versus controls	—
Ye 2001 et al. [88]	309 Caucasians (French) with T2DM versus 143 controls	TaqI, BsmI, Tru9I, ApaI	—	No statistical difference in genotype frequencies among cases versus controls	TT (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 controls	TaqI, ApaI	—	No statistical difference in genotype frequencies among cases versus controls	—