Is there a relationship between vitamin D with insulin resistance and diabetes mellitus?

Table 1 Accepted cut-off values of 25 hydroxyvitamin D3 (25OHD3) that describe vitamin D status

Vitamin D status	25OHD3 (nmol/L)1
Sufficient (optimal)	> 75
Insufficient	50-75
Deficient	< 50

¹Conversion factor, 1 nmol/L = 2.5 ng/mL.

Table 2 Data of selected epidemiological studies on the relation between vitamin D level and markers of insulin resistance (A), insulin resistance (B) and type 2 diabetes (C)

Ref.	No. of subjects	Age, mean or range	Trial outcome
(A)
Jorde et al[47]	10229	58	25OHD negatively associated with BMI
Lee et al[49]	95	68, 47-91	25OHD negatively related to BMI
Lagunova et al[50]	102	8-19	↑ prevalence of Vit D Def. (19%) and insuff. (> 50%) in obese
Suijder et al[60]	453	> 65	↑ BMI is associated with ↓ 25OHD
(B)
Chiu et al[27]	125	26	+ve relation between 25OHD and insulin sensitivity
Nunlee-Bland et al[51]	34	10-20	↓ 25OHD is associated with insulin resistance
Shankar et al[61]	12719	> 20	↓ 25OHD is associated with pre-diabetes state
(C)
Song et al[63]	76220	meta-analysis	inverse relation between 25OHD and risk for T2DM
Afzal et al[64]	9841	48-65	↓ 25OHD is associated with ↑ risk for T2DM
Pittas et al[65]	95243	meta-analysis	↓ incidence of T2DM in highest vs lowest 25OHD
Buijsse et al[69]	53088	50.9	HR of T2DM is ↓ with ↑ in 25OHD

T2DM:Type 2 diabetes mellitus; BMI: Body mass index.