Conundrum of vitamin D on glucose and fuel homeostasis

Table 8 Preventive trials of vitamin D supplementation to prevent the development of type 2 diabetes

Ref.	Country Race/ethnicity	Placebo control			Intervention			Dose	Frequency	Duration	Diabetes prevention
		n	25(OH)D nmol/L		n	25(OH)D nmol/L
			Initial	Final		Initial	Final
Dutta et al[134], 20141	IndiaAsian Indian	49	45	44	55	43	89	1500 μg	Weekly X 8, monthly	1 yr	Positive2
Niroomand et al[135], 2019	IranIranian	83	32	40	83	31	90	1250 μg	Weekly for 3 mo, monthly	6 mo	Positive3
Wagner et al[136], 20164	Sweden	22	47	46	21	42	83	750 μg	weekly	8 wk	Negative
Oosterwerff et al[137], 2014	HollandNon-Western	65	22	23	65	25	60	30 μg	daily	16 wk	Negative
Barengolts et al[141], 20155	United States African American	86	35	50	87	37	120	1250 μg	weekly	12 m	Negative
Davidson et al[139], 20136	United States Latino and African American	53	55	60	56	55	167	2222 μg	weekly	12 mo	Negative
Jorde et al[140], 2016	Norway	255	61	64	256	60	110	500 μg	weekly	5 yr	Negative
Pittas et al[138], 2019	United States mixed	1212	70	72	1211	69	136	100 μg	daily	24 mo	Negative

¹This study was an open label randomized design, instead of randomized placebo-control design as other studies.

²Intervention is associated with significantly lower progression to diabetes (11% vs 27%; P = 0.04) and higher reversal to normoglycemia (43% vs 20%; P = 0.02).

³The rate of progression toward diabetes was significantly lower in the intervention group (3% vs 28%; P = 0.002).

⁴Meadian 25-hydroxyvitamin was provided, rather than mean 25-hydroxyvitamin D as in other studies.

⁵Ergocalciferol was used, rather than cholecalciferol in other studies.

⁶Weekly dose of cholecalciferol was adjusted to titrate serum 25-hydroxyvitamin D between 162 nmol/L and 200 nmol/L.