Improving nutrition for the prevention of gestational diabetes: Current status and perspectives

Table 1 Summary of observational studies on the association of prenatal nutrition with the risk of gestational diabetes mellitus

Ref.	Population, sample size	Nutritional factors/diet pattern	Comparison	RR/OR of GDM (95%CI)
Zhang et al[32], 2006	13110 United States women	Fiber intake	Highest vs lowest quintile	RR 0.67 (0.51-0.90)
Zhang et al[30], 2006	13110 United States women	Western diet high in red meat and processed meat, refined grain products, sweets, fries, and pizza	Highest vs lowest quintile	RR 1.63 (1.20-2.21)
		“Prudent diet” characterized by high intake of fruit, green leafy vegetables, poultry, and fish	Lowest vs highest quintile	RR 1.39 (1.08-1.80)
Chen et al[24], 2009	13475 United States women	Sugar-sweetened cola	5 servings per week vs < 1 serving per month	RR 1.22 (1.01-1.47)
Bowers et al[25], 2011	13475 United States women	Heme iron intake	Highest vs lowest quintile	RR 1.58 (1.21-2.08)
Bowers et al[27], 2012	13475 United States women	Animal fat	Highest vs lowest quintile	RR 1.88 (1.36-2.60)
Tobias et al[31], 2012	15254 United States women	Mediterranean diet	Highest vs lowest quartile	RR 0.76 (0.60-0.95)
Bao et al[28], 2013	15294 United States women	Animal protein	Highest vs lowest quintile	RR 1.49 (1.03-2.17)
Bao et al[26], 2014	15027 United States women	Fried foods	> 7 times per week vs < 1 time per week	RR 1.88 (1.34-2.64)
Bao et al[29], 2014	15265 United States women	Diet low in carbohydrates but high in animal fat and protein	Highest vs lowest quartile	RR 1.36 (1.13-1.64)
Schoenaker et al[33], 2015	3853 Australian women	'Meats, snacks and sweets' pattern	Bottom and top tertiles of dietary pattern scores	RR 1.35 (0.98-1.81).
		'Mediterranean-style' pattern	Bottom and top tertiles of dietary pattern scores	RR 0.85 (0.76-0.98)
Popova et al[22], 2017	457 Russian women	Sausage	> 3 times per week vs less than once per week	OR 2.2 (1.2-4.1)
		Legumes	1-2 times per week vs less frequent consumption	OR 0.58 (0.36-0.94)

RR: Relative risk; OR: Odds ratio; CI: Confidence interval; GDM: Gestational diabetes mellitus.

Table 2 Summary of observational studies on the relationship between nutrition during pregnancy and the risk of gestational diabetes mellitus

Ref.	Population, sample size	Nutritional factors/diet pattern	Comparison	RR/OR of GDM (95%CI)
Radesky et al[52], 2008	1733 pregnant United States women	Diet type and frequency of red and processed meat consumption	Macronutrient energy partition and nutrient density substitution models	No association
Karamanos et al[37], 2014	Multicenter study of 10 Mediterranean countries, 1076 pregnant women	Mediterranean diet index (MDI), reflecting the degree of adherence to the MedDiet pattern of eating	Lower tertile of MDI (poor adherence) vs the upper tertile (good adherence)	OR 0.655(0.495-0.867)
He et al[42], 2015	3063 pregnant Chinese women	Vegetable pattern	Highest tertile vs lowest tertile	RR 0.79 (0.64-0.97)
		Protein-rich pattern		No association
		“Prudent” pattern		No association
		Sweets and seafood pattern		RR 1.23 (1.02-1.49)
Popova et al[22], 2017	680 pregnant Russian women	Fruit consumption	> 12 servings per week vs less consumption	OR 0.5 (0.3-0.8)
Elvebakk et al[50], 2018	702 pregnant Norwegian women	Intake of food groups	Women who developed GDM and women who did not develop GDM	No association
Liang et al[45], 2018	6299 Chinese pregnant women	Total protein	Highest tertile vs lowest tertile	RR 1.92 (1.10-3.14)
		Animal protein		RR 1.67 (1.19-2.93)
		Vegetable protein intake		No association
Assaf-Balut et al[38], 2018	874 Spanish women	Degree of adherence to a MedDiet pattern based on six food targets	High adherence (complying with 5-6 targets); moderate adherence (2-4 targets); low adherence (0-1 targets)	OR 0.35 (0.18-0.67)
Hu et al[43], 2019	1014 pregnant Chinese women	"Traditional pattern" (high vegetable, fruit, and rice intake)	Quartile 4 versus quartile 1	OR 0.44 (0.27-0.70)
		Whole grain-seafood pattern		OR 1.73, (1.10-2.74)

RR: Relative risk; OR: Odds ratio; CI: Confidence interval; GDM: Gestational diabetes mellitus.

Table 3 Summary of randomized trials on the effect of diet during pregnancy on the risk of gestational diabetes mellitus

Ref.	Design	Comparison	No. of participants (studies)	RR of GDM (95%CI)
Song et al[54], 2016	Meta-analysis, 27 RCTs (11487 women)	Lifestyle intervention of diet, PA or both vs standard management	11487 (27)	0.82 (0.70-0.95)
		PA plus diet vs standard management	6047 (14)	0.85 (0.70-1.03)
		Diet only vs standard management	1279 (5)	0.80 (0.58-1.10)
Tieu et al[53], 2017	Meta-analysis, 11 RCTs (2786 women)	Dietary recommendations vs standard treatment	1279 (5 RCTs)	0.60 (0.35-1.04); in overweight and obese women RR 0.39 (0.19-0.79)
		Low-glycemic index (GI) diet vs medium- or high-GI dietary recommendations	912 (4 RCTs)	0.91 (0.63-1.31)
		High-fiber diet vs standard dietary recommendations	25 (1)	No association
Shepherd et al[55], 2017	Meta-analysis, 23 RCTs (8918 women)	Combination of diet and exercise vs standard management	6633 (19)	0.85 (0.71-1.01)
Guo et al[56], 2019	Meta-analysis, 47 RCTs (15745 women)	Lifestyle intervention (diet, exercise, and mixed interventions) vs standard management	15745 (47)	0.77 (0.69-0.87)
		Diet alone vs standard management	2838 (11)	0.75 (0.60-0.95),

RR: Relative risk; PA: Physical activity; RCTs: Randomized clinical trials; CI: Confidence interval; GDM: Gestational diabetes mellitus.