Clinical case study on management of glycemic variability in gestational diabetes mellitus, diet as a primary therapeutic tool
Yamini. A.P*
Manager, Department of Clinical Dietetics, Kauvery Hospital, Alwarpet, Chennai, Tamil Nadu
*Correspondence
Introduction
A 26-year-old female patient conceived twin gestations via in vitro fertilization (IVF) with no prior history of diabetes mellitus. She subsequently developed gestational diabetes mellitus (GDM) during the course of pregnancy. The patient had a significant obstetric history, including two prior miscarriages (both IVF-conceived pregnancies complicated by GDM). Additionally, she presented a history of learning disability and poorly controlled hyperglycemia, with blood glucose levels consistently exceeding 200 mg/dL.
Following the implementation of individualized medical nutrition therapy (MNT), pharmacological intervention, continuous glucose monitoring (CGM), and close multidisciplinary follow-up, her glycemic control improved markedly. The patient maintained normoglycemic levels throughout the remainder of her pregnancy. The pregnancy culminated in the successful delivery of healthy twins via lower segment cesarean section (LSCS), with postnatal glycemic parameters remaining within normal physiological limits.
Background and Epidemiology
Gestational diabetes mellitus (GDM) is defined as glucose intolerance of variable severity with onset or first recognition during pregnancy (American Diabetes Association, 2024). It is one of the most common metabolic complications of pregnancy, with a global prevalence estimated at 13.9% of all pregnancies (International Diabetes Federation, 2021). In India, the prevalence of GDM ranges from 10% to 14.3%, with higher rates observed in urban populations (Seshiah et al., 2009).
The pathophysiology of GDM involves progressive insulin resistance mediated primarily by placental hormones, including human placental lactogen (hPL), progesterone, cortisol, and placental growth hormone. These hormones antagonize insulin action, leading to compensatory hyperinsulinemia. When pancreatic beta-cell function is insufficient to overcome this resistance, maternal hyperglycemia ensues (Plows et al., 2018).
Unmanaged GDM poses significant risks to both the mother and the fetus, including macrosomia, neonatal hypoglycemia, pre – eclampsia, cesarean delivery, and an increased long-term risk of type 2 diabetes mellitus in both the mother and offspring (HAPO Study Cooperative Research Group, 2008).
Screening and Diagnostic Criteria
The American Diabetes Association (ADA) and the American College of Obstetricians and Gynecologists (ACOG) recommend universal screening for GDM between 24 and 28 weeks of gestation. This timing corresponds to the period of maximal physiological insulin resistance induced by rising levels of placental hormones (ADA Standards of Care, 2024).
Target Glycemic Parameters
| Parameter | Target Value | Reference |
|---|---|---|
| Fasting Blood Glucose | < 95 mg/dL (5.3 mmol/L) | ADA, 2024 |
| 1-Hour Postprandial | < 140 mg/dL (7.8 mmol/L) | ADA, 2024 |
| 2-Hour Postprandial | < 120 mg/dL (6.7 mmol/L) | ADA, 2024 |
Goals of Medical Nutrition Therapy
Medical nutrition therapy (MNT) is the cornerstone of GDM management and should be initiated as first-line treatment upon diagnosis (Academy of Nutrition and Dietetics, 2018). The primary objectives of MNT in GDM include:
- Achieving and maintaining euglycemia while avoiding hypoglycemia and ketosis.
- Ensuring adequate caloric intake and optimal weight gain based on pre-pregnancy body mass index (BMI).
- Providing balanced macronutrient and micronutrient intake to support maternal health and fetal growth.
- Preventing obstetric and neonatal complications including macrosomia, neonatal hypoglycemia, shoulder dystopia, and preeclampsia.
Dietary Management Guidelines
Energy Requirements
During pregnancy, women require an additional 350 kcal/day above pre-pregnancy caloric needs during the second and third trimesters to support fetal growth and development (ICMR Revised RDA, 2024). For overweight or obese women with GDM (BMI > 25 kg/m²), a 30–33% caloric restriction is recommended, typically resulting in an intake of 1,600–1,800 kcal/day. This restriction must be carefully monitored to prevent ketonuria (Jovanovic-Peterson & Peterson, 1996).
Macro nutrient Distribution
| Macro nutrient | Recommended Intake | Clinical Guidance |
|---|---|---|
| Carbohydrates | ≥175 g/day (35–45% of total energy) | Emphasize complex carbohydrates from whole grains; legumes; fruits; and vegetables. Distribute evenly across meals and snacks to minimize postprandial glycemic excursions. |
| Protein | 55 g/day (20–25% of total energy) + 9.5 g/day (Trimester II) or + 22 g/day (Trimester III) | Include lean meats; fish; eggs; legumes; and plant-based protein sources. Adequate protein supports fetal tissue development. |
| Fat | 20–40% of total energy (≤10% saturated fat) | Prioritize monounsaturated and polyunsaturated fatty acids. Limit saturated fat intake. Include omega-3 fatty acids from fish and flaxseed. |
| Dietary Fiber | 28–30 g/day | Soluble fiber from oat bran; legumes; and pectin-rich fruits helps attenuate postprandial glucose spikes (WINGS-MOC Project). |
Reference: ICMR Revised Recommended Dietary Allowances (RDA), 2024.
Fluid and Electrolyte Recommendations
- Minimum fluid intake of 2.7 liters/day is recommended. Avoid fruit juices, tender coconut water, and carbonated beverages due to their high glycemic index.
- Sodium intake should be restricted to 1,500–2,300 mg/day (approximately 4 g of visible salt + 1 g of invisible salt per day).
Micronutrient Supplementation
| Micronutrient | Recommended Daily Intake | Clinical Notes |
|---|---|---|
| Vitamin D | 10 µg/day | Prescribed for women at risk of deficiency during pregnancy (NICE Guidelines 2015). |
| Folic Acid | 570 µg/day (+ 400 µg supplementation in first trimester) | Essential for neural tube development and prevention of megaloblastic anemia. |
| Calcium | 1000 mg/day | Supplementation advised if dietary calcium from dairy is insufficient (WHO 2013). |
| Iron | 27 mg/day | Supports the physiological increase in blood volume and fetal iron stores (ICMR 2024). |
Patient assessment and nutrition care process
Anthropometric Data
| Parameter | Value |
|---|---|
| Pre-pregnancy Weight | 92.6 kg |
| Height | 160.7 cm |
| Pre-pregnancy BMI | 35.8 kg/m² (Class II Obesity) |
| Ideal Body Weight (IBW) | 53.3 kg |
PES Statement (Problem-Etiology-Signs/Symptoms)
| Component | Description |
|---|---|
| Problem | Gestational Diabetes Mellitus with twin gestation (IVF-conceived) |
| Etiology | Strong familial history of diabetes; Class II obesity (BMI 35.8 kg/m²); IVF conception with twin gestation |
| Signs & Symptoms | Poorly controlled hyperglycemia (BGL > 200 mg/dL); history of two prior miscarriages due to GDM complications; co-morbid learning disability6.3 Subjective Global Assessment (SGA) |
The patient was classified as SGA rating score-18 (moderately malnourished/hyperglycemic), indicating the need for aggressive nutritional intervention alongside medical management.
Diet History
- Dietary pattern: Non-vegetarian.
- Known food allergies: None reported.
Management Plan I: Trimester II (26th Week)
Medical Management
Continuous glucose monitoring (CGM) was initiated to enable real-time tracking of glycemic fluctuations. CGM devices estimate interstitial glucose levels at regular intervals, providing comprehensive data on glucose trends, time in range (TIR), and glycemic variability (Dexcom, 2023). The following pharmacological regimen was prescribed:
| Medication | Dosage | Frequency |
|---|---|---|
| Inj. Novorapid (Insulin Aspart) | 25 units | With each meal |
| Inj. Novomix 30 (Biphasic Insulin Aspart) | 25 units | Night only |
| Tab. Glycomet 500mg (Metformin) | 500 mg | Three times daily (1-1-1) |
Nutritional Management
- 24 recall method obtained from patient clearly shows eractic food choices and high calorie dense foods consumption.
- Delivering around 1660 kilo calories, 59 gms protein, 248 gms carbohydrate& 32 gms fat.
- Strict glycemic control through 3 major + 3 minor meals focusing on complex carbohydrates from whole grains, fruits, vegetables.
- The nutritional plan followed during the second trimester and third trimester (26th week-32nd week).
Nutritional Prescription (26th Week)
| Energy | 1,600 kcal/day |
| Carbohydrate | 200 g/day (50% of total kcal) |
| Protein | 62 g + 9.5 g (Trimester II) = 71.5 g/day |
| Fat | 35 g/day (20% of total kcal) |
| Fluids | Liberal intake (minimum 2.7 L/day) |
| Supplements | As per ICMR RDA 2024 recommendations |
Trimester II Menu Plan
| Timing | Menu Options |
|---|---|
| Early Morning 7:00 am | Skimmed milk / Tea / Coffee – 150 mL (without sugar) |
| Breakfast 9:00 am | Idly / Chapathi / Ragi Adai / Wheat Dosa – 3 nos. OR Wheat Upma / Kitchadi – 1½ cup (150 g cooked) OR Brown Bread – 4 slices with Sambar / Chutney – ½ cup |
| Mid-Morning 11:00 am | Skimmed Buttermilk / Vegetable Soup – 200 mL; Fruit (Apple / Guava / Papaya / Pears / Muskmelon) – 100 g |
| Lunch 1:00 pm | Rice – 1½ cup or Chapathi – 3 nos.; Vegetable preparation – 2 cups (preferably green vegetables); Curd – 100 mL; Non-veg: Egg white (2 nos.) or Chicken/Fish (150 g) – thrice weekly |
| Evening 4:00 pm | Skimmed Milk / Tea / Coffee – 150 mL; Sundal – 50 g OR Marie Light / Digestive biscuits – 3 nos. |
| Dinner 7:30 pm | Same options as breakfast with Sambar / Chutney – ½ cup; Preferably wheat-based products |
| Bedtime 9:00 pm | Skimmed Milk – 150 mL (without sugar) |
Nutritive Value Analysis (Trimester II)
| Ingredient | Quantity | Energy (kcal) | Protein (g) | CHO (g) | Fat (g) |
|---|---|---|---|---|---|
| Skimmed Milk | 450 mL | 285 | 14.1 | 15 | 15 |
| Idly | 3 nos. | 255 | 9.0 | 26 | 4.0 |
| Sambar | 1 cup | 170 | 9.5 | 12 | 0 |
| Chutney | 1 cup | 50 | 1.8 | 3.0 | 0.3 |
| Buttermilk | 300 mL | 35 | 2.4 | 2.3 | 4.0 |
| Apple | 100 g | 40 | – | 10 | – |
| Wheat Upma | 1 cup | 120 | 3.0 | 17 | – |
| Non-veg (Chicken/Fish) | 150 g | 220 | 9.0 | 28 | 6.0 |
| Egg White | 2 nos. | 40 | 12.0 | – | – |
| Vegetables | 2 cups | 120 | 3.0 | 13 | 1.0 |
| Rice | 1 cup | 170 | 3.2 | 22 | – |
| Curd | 100 mL | 60 | 3.1 | 3.0 | 4.0 |
| Sundal | 50 g | 85 | 5.6 | 14 | 0 |
| Chapathi | 1 no. | 85 | 2.5 | 11 | 0.2 |
| Total | - | 1,630 kcal | Protein: 74 g | CHO: 176.3 g | Fat: 34.5 g |
CGM Data Analysis: 26th Week
Fasting Blood Glucose (6:00 am) – Target: < 95 mg/dL
| Day 1 | Day 2 | Day 3 | Day 4 | Day 5 | Day 6 | Day 7 |
|---|---|---|---|---|---|---|
| 117 mg/dL | 123 mg/dL | 132 mg/dL | 93 mg/dL | 113 mg/dL | 115 mg/dL | 103 mg/dL |
Observation: Fasting glucose levels remained elevated above target on 6 of 7 days, indicating inadequate overnight glycemic control prior to dietary intervention optimization.
Postprandial Blood Glucose (11.00 am) – Target: < 140 mg/dL
| Day 1 | Day 2 | Day 3 | Day 4 | Day 5 | Day 6 | Day 7 |
|---|---|---|---|---|---|---|
| 260 mg/dL | 252 mg/dL | 220 mg/dL | 215 mg/dL | 187 mg/dL | 164 mg/dL | 116 mg/dL |
Observation: Postprandial levels were markedly elevated early in the week, demonstrating a progressive downward trend following initiation of structured MNT and insulin titration.
Management Plan II: Trimester III (27TH–32ND week)
Nutritional Prescription (Trimester III)
| Energy | 1,600 kcal/day |
| Carbohydrate | 200 g/day (50% of total kcal) |
| Protein | 62 g + 22 g (Trimester III) = 84 g/day |
| Fat | 35 g/day (20% of total kcal) |
| Fluids | Liberal intake (minimum 2.7 L/day) |
| Supplements | As per ICMR RDA 2024 recommendations |
Trimester III Menu Plan
| Timing | Menu Options |
|---|---|
| Early Morning 7:00 am | Skimmed milk / Tea / Coffee – 150 mL (without sugar) |
| Breakfast 9:00 am | Millet Idly / Chapathi / Ragi Adai / Pesarattu – 3 nos. OR Wheat Upma / Poha Upma / Kitchadi – 1½ cup OR Brown Bread – 4 slices with Sambar / Chutney – ½ cup |
| Mid-Morning 11:00 am | Skimmed Buttermilk / Vegetable Soup – 200 mL; Fruit (Apple / Guava / Papaya / Pears / Muskmelon) – 100 g |
| Lunch 1:00 pm | Rice / Brown Rice – 1½ cup or Jowar Roti – 3 nos.; Vegetable preparation – 2 cups (green vegetables); Curd – 100 mL; Non-veg: Egg white (2 nos.) or Chicken/Fish (150 g) – thrice weekly |
| Evening 4:00 pm | Skimmed Milk / Tea / Coffee – 150 mL; Sprouts / Sundal – 50 g OR Millet / Digestive biscuits – 3 nos. |
| Dinner 7:30 pm | Same options as breakfast; Preferably millet and wheat-based products |
| Bedtime 9:00 pm | Skimmed Milk – 150 mL (without sugar) |
Nutritive Value Analysis (Trimester III)
| Ingredient | Quantity | Energy (kcal) | Protein (g) | CHO (g) | Fat (g) |
|---|---|---|---|---|---|
| Skimmed Milk | 450 mL | 285 | 14.1 | 15 | 15 |
| Millet Idly | 4 nos. | 285 | 16.0 | 22 | 3.0 |
| Sambar | 1 cup | 100 | 9.5 | 12 | 0 |
| Chutney | 1 cup | 30 | 1.8 | 3.0 | 0.3 |
| Buttermilk | 300 mL | 35 | 2.4 | 2.3 | 4.0 |
| Apple | 100 g | 40 | – | 10 | – |
| Wheat / Poha Upma | 1 cup | 120 | 3.0 | 17 | – |
| Non-veg (Chicken/Fish) | 150 g | 220 | 9.0 | 28 | 6.0 |
| Egg White | 2 nos. | 40 | 12.0 | 13 | – |
| Vegetables | 2 cups | 120 | 3.0 | – | 1.0 |
| Rice / Brown Rice | 1 cup | 120 | 3.0 | 25 | – |
| Curd | 100 mL | 60 | 3.1 | 3.0 | 4.0 |
| Sundal / Sprouts | 50 g | 85 | 5.6 | 14 | 0 |
| Chapathi / Jowar Roti | 1 no. | 85 | 3.0 | 11 | 1.0 |
| Total | - | 1,625 kcal | Protein: 85 g | CHO: 175.3 g | Fat: 34.3 g |
CGM Data Analysis: 27th–32nd Week
Fasting Blood Glucose (6:00 am) – Target: < 95 mg/dL
| Day 1 | Day 2 | Day 3 | Day 4 | Day 5 | Day 6 | Day 7 |
|---|---|---|---|---|---|---|
| 108 mg/dL | 103 mg/dL | 101 mg/dL | 98 mg/dL | 94 mg/dL | 92 mg/dL | 90 mg/dL |
Observation: A clear downward trend was observed, with fasting glucose reaching target levels (< 95 mg/dL) by Day 5, indicating effective glycemic control through sustained dietary modification and insulin optimization.
Postprandial Blood Glucose (12:00 pm) – Target: < 140 mg/dL
| Day 1 | Day 2 | Day 3 | Day 4 | Day 5 | Day 6 | Day 7 |
|---|---|---|---|---|---|---|
| 162 mg/dL | 155 mg/dL | 114 mg/dL | 114 mg/dL | 118 mg/dL | 101 mg/dL | 105 mg/dL |
Observation: Postprandial glucose levels normalized by Day 3 and remained within target for the remainder of the monitoring period, demonstrating the efficacy of the combined dietary and pharmacological approach.
Challenges Encountered
Several challenges were encountered during the dietary management of this patient with GDM and twin gestation:
- Dietary non-adherence: The patient intermittently deviated from the prescribed meal plan and occasionally skipped meals, contributing to glycemic variability.
- Craving management: Pregnancy-related cravings for sweets and refined carbohydrates posed a significant challenge to maintaining the carbohydrate-controlled diet.
- Portion control: Inconsistent portion sizes led to fluctuations in blood glucose levels, requiring repeated dietary counseling.
- Food aversions: Pregnancy-associated food aversions limited the variety of nutrient-dense foods the patient could tolerate.
- Carbohydrate monitoring: Accurate carbohydrate counting and coordination with insulin dosing required intensive patient education.
- Social eating situations: Managing GDM-appropriate dietary choices during social gatherings and dining out presented additional difficulties.
Case Outcome and Summary
A 26-year-old female with twin gestation (IVF-conceived) was admitted with pre-diabetes that progressed to gestational diabetes mellitus. She presented with a history of learning disability, poorly controlled hyperglycemia (blood glucose > 200 mg/dL), Class II obesity (BMI 35.8 kg/m²), and a strong familial predisposition to diabetes.
Through the implementation of a structured, individualized medical nutrition therapy plan complemented by insulin therapy and continuous glucose monitoring, significant glycemic improvement was achieved. Both fasting and postprandial glucose levels were brought within target ranges by the 32nd week of gestation.
The pregnancy was successfully extended to the 35th week, surpassing the originally planned cesarean delivery date, under the guidance of Dr. K. Baraneedharan, Senior Consultant Dialectologist, and the clinical dietetics team at Kauvery Hospital. The patient delivered healthy twins via lower segment cesarean section (LSCS), with postnatal glycemic parameters remaining within normal limits.
This case underscores the critical role of medical nutrition therapy as a primary therapeutic modality in the management of gestational diabetes mellitus, particularly in high-risk pregnancies complicated by obesity and twin gestation.
References
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- Plows, J. F., Stanley, J. L., Baker, P. N., et al. (2018). The pathophysiology of gestational diabetes mellitus. International Journal of Molecular Sciences, 19(11), 3342.
- HAPO Study Cooperative Research Group. (2008). Hyperglycemia and adverse pregnancy outcomes. New England Journal of Medicine, 358(19), 1991–2002.
- Academy of Nutrition and Dietetics. (2018). Gestational Diabetes Evidence-Based Nutrition Practice Guideline. Chicago, IL: Academy of Nutrition and Dietetics.
- Indian Council of Medical Research (ICMR). (2024). Revised Recommended Dietary Allowances for Indians. New Delhi: ICMR-National Institute of Nutrition.
- Jovanovic-Peterson, L., & Peterson, C. M. (1996). Dietary manipulation as a primary treatment strategy for pregnancies complicated by diabetes. Journal of the American College of Nutrition, 15(1), 23–31.
- National Institute for Health and Care Excellence (NICE). (2015). Diabetes in Pregnancy: Management from Preconception to the Postnatal Period. NICE Guideline [NG3].
- World Health Organization (WHO). (2013). Guideline: Calcium Supplementation in Pregnant Women. Geneva: WHO.
- WINGS-MOC Project. (2020). Whole grains, dairy, and dietary fibre effects on neonatal outcomes in women with gestational diabetes mellitus.
- Dexcom, Inc. (2023). Continuous Glucose Monitoring Systems: Clinical Evidence and Guidelines. San Diego, CA: Dexcom.
