**1.5. Medical nutritional therapy**

Prevention of diabetes, providing good glycemic control in existing diabetes, and decreasing the rate of development of diabetic complications are the primary goals of medical nutrition therapy (MNT). All diabetic patients should have an individualized MNT, ideally prepared by a registered dietitian who is knowledgeable and experienced in the management of GDM [32].

Prenatal MNT should provide a meal plan to optimize blood glucose management. Woman's food and eating habits and plasma glucose responses should drive the energy distribution and carbohydrate intake throughout gestation. Since glucose goes through fetus from the mother, the times of food and regular meals and snacks taken are vital to prevent hypoglycemia. Monitoring of plasma glucose and daily food records maintains important information for insulin dosing and meal plan modifications. Sufficient maternal and fetal nutrition, energy taking for adequate weight gain, and all essential vitamin and mineral supplements are primary components of the MNT [26, 32].

The composition of a diabetic diet should be consistent with that for nonpregnant diabetic women and include all the necessary macronutrients and micronutrients in appropriate amounts for growth and development of the fetus.

MNT for GDM should maintain maternal and fetal health with sufficient energy levels providing adequate gestational weight gain, obtainment, continuity of normoglycemia, and lack of ketones. Carbohydrate intake should be divided into three small- to moderate-sized meals and two to four snacks. An evening snack might be recommended in avoiding accelerated ketosis night long [32]. Strict calorie restriction may lead to ketosis as a result of accelerated fat catabolism which is associated with altered psychomotor development [33].

#### **1.6. Energy**

GDM patients should have at least four blood glucose measurement daily (fasting and 1 h after the first bite of each meal) to monitor hyperglycemia that is known to increase the risk of adverse maternal and fetal outcomes. One-hour postprandial glucose monitoring provides a better glycemic control and fewer cases of large-for-gestational age infants compared to fasting glucose monitoring [21]. Postprandial monitoring provides a better glycemic control and

GDM is associated with higher macrosomia risk and birth complications and an increased risk of maternal type 2 diabetes postpartum [3]. Diet, exercise, and lifestyle changes may decrease the risk of GDM [24, 25]. Lifestyle modification alone is sufficient in most of the patients to control GDM [26, 27]. However, early initiation of pharmacologic therapy might

Insulin is the recommended first-line agent in the treatment of GDM. Although randomized controlled trials demonstrated the efficacy and short-term safety of metformin [28, 29] and

Prevention of diabetes, providing good glycemic control in existing diabetes, and decreasing the rate of development of diabetic complications are the primary goals of medical nutrition therapy (MNT). All diabetic patients should have an individualized MNT, ideally prepared by a registered dietitian who is knowledgeable and experienced in the management of

Prenatal MNT should provide a meal plan to optimize blood glucose management. Woman's food and eating habits and plasma glucose responses should drive the energy distribution and carbohydrate intake throughout gestation. Since glucose goes through fetus from the mother, the times of food and regular meals and snacks taken are vital to prevent hypoglycemia. Monitoring of plasma glucose and daily food records maintains important information for insulin dosing and meal plan modifications. Sufficient maternal and fetal nutrition, energy taking for adequate weight gain, and all essential vitamin and mineral supplements are pri-

The composition of a diabetic diet should be consistent with that for nonpregnant diabetic women and include all the necessary macronutrients and micronutrients in appropriate

MNT for GDM should maintain maternal and fetal health with sufficient energy levels providing adequate gestational weight gain, obtainment, continuity of normoglycemia, and lack of ketones. Carbohydrate intake should be divided into three small- to moderate-sized meals and two to four snacks. An evening snack might be recommended in avoiding accelerated ketosis night long [32]. Strict calorie restriction may lead to ketosis as a result of accelerated fat catabolism which is associated with altered psychomotor

be needed when lifestyle modifications are insufficient for glycemic control.

glyburide [30], long-term safety trials are still lacking for any oral drugs [31].

lower risk of preeclampsia [22, 23].

**1.5. Medical nutritional therapy**

mary components of the MNT [26, 32].

amounts for growth and development of the fetus.

GDM [32].

148 Diabetes Food Plan

development [33].

Most of the patients with GDM are obese, and additional weight increase during pregnancy leads to adverse pregnancy outcome and long-term risk for development of T2DM. The recommendation of minimal weight gain in obese GDM patients has not been confirmed yet. Weight gain in pregnancy should represent pregestational weight [9].

Although significant caloric restriction in obese GDM patients may cause ketosis, moderate caloric restriction (decrease by 30% of estimated energy requirements) in these patients may provide a good glycemic control without ketonemia and decrease maternal weight gain. The data regarding how such diets have impact on fetal outcomes are lacking [34]. Recommendations for weight gain during pregnancy were shown in **Table 1**.

Adequate energy intake is recommended for proper weight gain. Moderate energy and carbohydrate limitation are recommended, instead of weight loss, for overweight, and obese GDM patients. The primary goals of MNT for GDM are proper weight gain, normoglycemia, and absence of ketosis [34]. The requirement for energy does not rise in the first trimester of gestation. An additional 300 kcal/day is recommended to compensate the increase in maternal blood flow, breast, uterus, adipose tissue, placental growth, fetal growth, and amniotic fluids after the first trimester. Nevertheless, a safe pregnancy is possible with lower energy intake [36]. Quality nutritional intake is required. A number of calories should be calculated according to ideal body weight. The recommendations for daily calorie intake were shown in **Table 2**.

Calorie recommendations may provide normoglycemia in 75–80% of GDM [4]. Reduction in caloric intake by 30–33% would help blood glucose management without increasing ketosis risk in obese women with GDM. Nevertheless, the caloric intake should not be less than 1600–1800 kcal/ day. In cases of calorie reduction, urine should be monitored for ketones. Catabolic metabolism and malnutrition of fetus must be prevented.

The recommended overall dietary ratio: Carbohydrates: 40–50%, protein: 20–25%, and fat: 30–35%. Although restriction of carbohydrate intake to 40–45% of daily energy decreases postprandial glucose, the ratio of carbohydrates should not be lower than 40% [37].


**Table 1.** Recommendations for weight gain and rate of weight gain during pregnancy [35].


effect on plasma lipid levels. Nevertheless, no studies support the avoidance of consuming

Medical Nutrition Therapy for Special Groups with Diabetes Mellitus

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151

Consuming Food and Drug Administration (FDA) or the European Food Safety Agency (EFSA) verified acceptable daily intake of sugar alcohols and noncaloric sweeteners are considered safe according to limited human studies. Aspartame (with the exception of women suffering from phenylketonuria), acesulfame potassium, sucralose, neotame, advantage, steviol glycosides, and extracts from monk fruit are all FDA-approved noncaloric sweeteners for use during pregnancy. Cyclamates and its salts are currently forbidden in the USA; however, data related to consuming these agents in patients with GDM

Protein intake is very important during pregnancy to compensate the increase in protein synthesis, maintaining maternal tissues and fetal growth, and especially during the third trimester. Low protein intake may have negative effects on weight and length at birth; however, high intake may worsen fetal development [43]. A diet with appropriate protein (0.75 g/kg/day plus an additional 10 g/day) is also necessary for pregnant women. The necessity of nutrient composition during gestation and lactation is not different in women with and without diabetes [36]. Proteins and amino acids in the diet are significant regulators of glucose homeostasis, and a high-protein diet contributes to insulin resistance and increases gluconeogenesis [44]. The amount of protein in the diet should be about 20–25% of the total energy intake, with a minimum of 60–80 g/day according to the German Diabetes Association and German Association for Gynaecology and Obstetrics (DDG-DGGG) [42].

Limitation of carbohydrate intake often leads to higher fat intake as protein intake should remain constant at 15–20%. High-fat diet causes an increase in free fatty acid levels which contribute to insulin resistance. Studies in nonhuman primates and human demonstrated that high-fat diet leads to fetal fat accumulation and increase in fetal adipose tissue and contributes to hepatosteatosis, increase in inflammation and oxidative stress, and impairment of

Limitation of carbohydrate intake increases the ratio of total calories provided from protein and fat to ensure overall energy requirements; however, the data about how the type of dietary fats and carbohydrates affects glycemic control GDM patients are insufficient. Low versus high glycemic foods and monounsaturated fat (MUFAs) versus polyunsaturated fatty acids in the diet have a better impact on glycemic control in nonpregnant patients with T2DM. Gunderson et al. demonstrated that addition of saturated fatty acids to the diet resulted in lower postprandial glucose and insülin response compared to the addition of MUFAs [45]. A recent meta-analysis evaluating the effects of a diet with high MUFAs in T2DM patients found a reduction in fasting blood glucose, postprandial glucose, and whole-day blood glu-

fructose found in fruits, vegetables, and other foods [41].

are lacking [42].

**1.8. Protein**

**1.9. Fat**

glucose uptake in muscles [39].

cose and insulin concentrations [46].

**Table 2.** The recommendations for daily calorie intake per kg of body weight are.

#### **1.7. Carbohydrate**

A specific glucose transporter carries glucose through placenta by a glucose level dependent process. GDM leads to upregulation of these transporters. Glucose transfer is highest during the postprandial period, and decreasing postprandial glucose has a bigger effect on reducing increased fetal growth. Therefore, MNT for GDM should be a focus on decreasing postprandial glucose [9].

The amount and ratio of carbohydrate should be calculated according to clinical outcome measures such as hunger, plasma glucose levels, weight gain, and ketone levels; however, daily carbohydrate should not be less than 175 gr. Total calculated carbohydrate should be divided into three small- to moderate-sized meals and two to four snacks. An evening snack might be added to avoid night long ketosis. Carbohydrate is generally better tolerated at other meals when compared to breakfast [34]. Hence, breakfast cereals with high glycemic index should be switched with more slowly absorbed carbohydrates [9]. A total of 15–30 g of carbohydrates are suggested for breakfast [37]. Small frequent meals with slowly absorbed carbohydrates are very helpful in reducing fasting ketosis which is known to have a negative impact on fetal cognitive development [9].

The glycemic index is a relative measure of a food's carbohydrate content by its impact on postprandial glucose levels. The combination of carbohydrates with high glycemic index and low-cereal-fiber diet could lead to 2.15 fold increase in GDM risk when compared to the reciprocal diet [38]. Decreasing the rate of carbohydrate digestion and absorption and consumption of low glycemic index (LGI) containing foods reduce postprandial blood glucose levels as well as fasting blood glucose [2, 33]. Carbohydrate ratio of >45% in the total energy has a negative impact on glycemic control; however, up to 60% carbohydrate ratio with low-glycemic-index carbohydrates do not have a detrimental effect on glucose tolerance in pregnancy [9]. A diet which is high in carbohydrates of LGI have a positive impact on postprandial glycemic control in nondiabetic pregnants, GDM patients, nonpregnant type 1, and type 2 diabetics. This diet also decreases the required insulin dose in GDM patients [39]. Although an LGI diet has favorable impact on gestational weight gain and maternal glycemic control, it does not decrease the incidence of large for gestational age infants with high risk for fetal macrosomia [40].

High dietary fiber has a positive effect on glycemic control in pregnant women with diabetes, and at least 24-g daily fiber is recommended for all women. Although fructose provides more favorable postprandial glucose when it switches sucrose or starch in the diet, it has a negative effect on plasma lipid levels. Nevertheless, no studies support the avoidance of consuming fructose found in fruits, vegetables, and other foods [41].

Consuming Food and Drug Administration (FDA) or the European Food Safety Agency (EFSA) verified acceptable daily intake of sugar alcohols and noncaloric sweeteners are considered safe according to limited human studies. Aspartame (with the exception of women suffering from phenylketonuria), acesulfame potassium, sucralose, neotame, advantage, steviol glycosides, and extracts from monk fruit are all FDA-approved noncaloric sweeteners for use during pregnancy. Cyclamates and its salts are currently forbidden in the USA; however, data related to consuming these agents in patients with GDM are lacking [42].

#### **1.8. Protein**

**1.7. Carbohydrate**

150 Diabetes Food Plan

dial glucose [9].

impact on fetal cognitive development [9].

A specific glucose transporter carries glucose through placenta by a glucose level dependent process. GDM leads to upregulation of these transporters. Glucose transfer is highest during the postprandial period, and decreasing postprandial glucose has a bigger effect on reducing increased fetal growth. Therefore, MNT for GDM should be a focus on decreasing postpran-

**BMI Daily calorie intake**

Underweight < 18.5 35–40 kcal/kg Normal 18.5–24.9 30–34 kcal/kg Overweight 25.0–29.9 25–29 kcal/kg Obese >30 24 kcal/kg

**Table 2.** The recommendations for daily calorie intake per kg of body weight are.

The amount and ratio of carbohydrate should be calculated according to clinical outcome measures such as hunger, plasma glucose levels, weight gain, and ketone levels; however, daily carbohydrate should not be less than 175 gr. Total calculated carbohydrate should be divided into three small- to moderate-sized meals and two to four snacks. An evening snack might be added to avoid night long ketosis. Carbohydrate is generally better tolerated at other meals when compared to breakfast [34]. Hence, breakfast cereals with high glycemic index should be switched with more slowly absorbed carbohydrates [9]. A total of 15–30 g of carbohydrates are suggested for breakfast [37]. Small frequent meals with slowly absorbed carbohydrates are very helpful in reducing fasting ketosis which is known to have a negative

The glycemic index is a relative measure of a food's carbohydrate content by its impact on postprandial glucose levels. The combination of carbohydrates with high glycemic index and low-cereal-fiber diet could lead to 2.15 fold increase in GDM risk when compared to the reciprocal diet [38]. Decreasing the rate of carbohydrate digestion and absorption and consumption of low glycemic index (LGI) containing foods reduce postprandial blood glucose levels as well as fasting blood glucose [2, 33]. Carbohydrate ratio of >45% in the total energy has a negative impact on glycemic control; however, up to 60% carbohydrate ratio with low-glycemic-index carbohydrates do not have a detrimental effect on glucose tolerance in pregnancy [9]. A diet which is high in carbohydrates of LGI have a positive impact on postprandial glycemic control in nondiabetic pregnants, GDM patients, nonpregnant type 1, and type 2 diabetics. This diet also decreases the required insulin dose in GDM patients [39]. Although an LGI diet has favorable impact on gestational weight gain and maternal glycemic control, it does not decrease the

incidence of large for gestational age infants with high risk for fetal macrosomia [40].

High dietary fiber has a positive effect on glycemic control in pregnant women with diabetes, and at least 24-g daily fiber is recommended for all women. Although fructose provides more favorable postprandial glucose when it switches sucrose or starch in the diet, it has a negative Protein intake is very important during pregnancy to compensate the increase in protein synthesis, maintaining maternal tissues and fetal growth, and especially during the third trimester. Low protein intake may have negative effects on weight and length at birth; however, high intake may worsen fetal development [43]. A diet with appropriate protein (0.75 g/kg/day plus an additional 10 g/day) is also necessary for pregnant women. The necessity of nutrient composition during gestation and lactation is not different in women with and without diabetes [36]. Proteins and amino acids in the diet are significant regulators of glucose homeostasis, and a high-protein diet contributes to insulin resistance and increases gluconeogenesis [44]. The amount of protein in the diet should be about 20–25% of the total energy intake, with a minimum of 60–80 g/day according to the German Diabetes Association and German Association for Gynaecology and Obstetrics (DDG-DGGG) [42].

#### **1.9. Fat**

Limitation of carbohydrate intake often leads to higher fat intake as protein intake should remain constant at 15–20%. High-fat diet causes an increase in free fatty acid levels which contribute to insulin resistance. Studies in nonhuman primates and human demonstrated that high-fat diet leads to fetal fat accumulation and increase in fetal adipose tissue and contributes to hepatosteatosis, increase in inflammation and oxidative stress, and impairment of glucose uptake in muscles [39].

Limitation of carbohydrate intake increases the ratio of total calories provided from protein and fat to ensure overall energy requirements; however, the data about how the type of dietary fats and carbohydrates affects glycemic control GDM patients are insufficient. Low versus high glycemic foods and monounsaturated fat (MUFAs) versus polyunsaturated fatty acids in the diet have a better impact on glycemic control in nonpregnant patients with T2DM. Gunderson et al. demonstrated that addition of saturated fatty acids to the diet resulted in lower postprandial glucose and insülin response compared to the addition of MUFAs [45]. A recent meta-analysis evaluating the effects of a diet with high MUFAs in T2DM patients found a reduction in fasting blood glucose, postprandial glucose, and whole-day blood glucose and insulin concentrations [46].
