🍎Medical Nutrition Therapy I Unit 9 – Diabetes: Nutrition Therapy & Management

What is Diabetes?

• Diabetes is a chronic metabolic disorder characterized by elevated blood glucose levels (hyperglycemia) resulting from defects in insulin secretion, insulin action, or both
• Insulin, a hormone produced by the pancreas, regulates the body's use and storage of glucose
• In diabetes, the body either does not produce enough insulin or does not effectively use the insulin it produces, leading to high blood sugar levels
• Chronic hyperglycemia can lead to serious complications affecting various organs and systems in the body, such as the eyes, kidneys, nerves, heart, and blood vessels
• The three main types of diabetes are Type 1 Diabetes, Type 2 Diabetes, and Gestational Diabetes
• Prediabetes is a condition where blood glucose levels are higher than normal but not high enough to be diagnosed as diabetes, increasing the risk of developing Type 2 Diabetes

Types of Diabetes

• Type 1 Diabetes (T1D) is an autoimmune disorder in which the body's immune system attacks and destroys the insulin-producing beta cells in the pancreas
  • Accounts for 5-10% of all diabetes cases
  • Usually diagnosed in children, adolescents, or young adults
  • Requires lifelong insulin therapy to manage blood glucose levels
• Type 2 Diabetes (T2D) is a progressive condition where the body becomes resistant to insulin or the pancreas fails to produce enough insulin to maintain normal blood glucose levels
  • Accounts for 90-95% of all diabetes cases
  • Often associated with obesity, physical inactivity, and older age
  • Can be managed through lifestyle modifications, oral medications, and sometimes insulin therapy
• Gestational Diabetes (GDM) develops during pregnancy due to hormonal changes that make the body less responsive to insulin
  • Affects approximately 2-10% of pregnancies
  • Usually resolves after delivery but increases the risk of developing T2D later in life
  • Requires close monitoring and management to prevent complications for both mother and baby
• Other types of diabetes include Latent Autoimmune Diabetes in Adults (LADA), Maturity-Onset Diabetes of the Young (MODY), and diabetes caused by specific conditions (pancreatitis) or medications (glucocorticoids)

Pathophysiology and Risk Factors

• In T1D, the immune system mistakenly attacks and destroys the insulin-producing beta cells in the pancreas, leading to little or no insulin production
  • Genetic predisposition and environmental triggers (viral infections) play a role in the development of T1D
• In T2D, the body becomes resistant to insulin's action, and the pancreas may not produce enough insulin to overcome this resistance
  • Insulin resistance occurs when cells in the liver, muscle, and fat tissue do not respond properly to insulin, leading to impaired glucose uptake and utilization
  • Over time, the pancreas may fail to produce sufficient insulin to maintain normal blood glucose levels
• Risk factors for T2D include obesity, physical inactivity, age (≥45 years), family history of diabetes, race/ethnicity (African American, Hispanic/Latino, Native American, Asian American, Pacific Islander), and history of GDM or prediabetes
• Obesity, particularly abdominal obesity, is a major risk factor for T2D as it contributes to insulin resistance
  • Excess adipose tissue releases inflammatory cytokines and free fatty acids that impair insulin signaling and glucose uptake
• Physical inactivity reduces insulin sensitivity and glucose uptake by skeletal muscles, increasing the risk of T2D
• Aging is associated with a decline in beta cell function and increased insulin resistance, elevating the risk of T2D

Diagnosis and Monitoring

• Diabetes is diagnosed based on plasma glucose criteria, either fasting plasma glucose (FPG), 2-hour plasma glucose (2-h PG) during a 75-g oral glucose tolerance test (OGTT), or A1C criteria
  • FPG ≥126 mg/dL (7.0 mmol/L), 2-h PG ≥200 mg/dL (11.1 mmol/L) during OGTT, or A1C ≥6.5% (48 mmol/mol) indicates diabetes
  • FPG 100-125 mg/dL (5.6-6.9 mmol/L), 2-h PG 140-199 mg/dL (7.8-11.0 mmol/L) during OGTT, or A1C 5.7-6.4% (39-47 mmol/mol) indicates prediabetes
• A1C reflects average blood glucose levels over the past 2-3 months and is used for both diagnosis and monitoring of diabetes management
  • A1C should be measured at least twice a year in patients meeting treatment goals and quarterly in patients not meeting goals or with changes in therapy
• Self-monitoring of blood glucose (SMBG) using a glucometer helps patients assess their response to therapy and achieve glycemic goals
  • Frequency and timing of SMBG depend on the patient's treatment regimen, glycemic control, and individual needs
• Continuous glucose monitoring (CGM) systems provide real-time glucose readings and trends, helping patients and healthcare providers make informed decisions about diabetes management
• Regular monitoring of blood pressure, lipid profile, kidney function, and foot and eye health is essential for preventing and detecting diabetes-related complications

Nutritional Management Basics

• Medical nutrition therapy (MNT) is a crucial component of diabetes management that aims to optimize glycemic control, maintain a healthy weight, and prevent or delay complications
• Individualized nutrition plans should consider the patient's age, cultural background, personal preferences, and treatment goals
• Key principles of MNT for diabetes include achieving and maintaining a healthy body weight, consuming a balanced diet with a variety of nutrient-dense foods, and monitoring carbohydrate intake
• A registered dietitian (RD) or registered dietitian nutritionist (RDN) should be involved in the development and implementation of the nutrition plan
• Calorie needs are determined based on the patient's age, sex, weight, height, physical activity level, and treatment goals (weight loss, weight maintenance, or weight gain)
• Macronutrient distribution recommendations:
  • Carbohydrates: 45-65% of total daily calories, with an emphasis on whole grains, fruits, vegetables, and low-fat dairy products
  • Protein: 15-20% of total daily calories, with a focus on lean meats, fish, poultry, eggs, and plant-based proteins (legumes, nuts, seeds)
  • Fat: 20-35% of total daily calories, with a focus on healthy fats (monounsaturated and polyunsaturated) and limited intake of saturated and trans fats
• Consistent meal timing and spacing help maintain stable blood glucose levels and prevent hypoglycemia, especially for patients on insulin or insulin secretagogues

Carbohydrate Counting and Meal Planning

• Carbohydrate counting is a meal planning approach that helps patients manage their blood glucose levels by monitoring the amount of carbohydrates consumed at each meal or snack
• Carbohydrates have the greatest impact on postprandial blood glucose levels, making them the primary focus of meal planning for diabetes management
• The three main types of carbohydrates are starches (bread, pasta, rice), sugars (natural and added), and fiber (non-digestible carbohydrates)
• One carbohydrate serving (or "carb choice") is equivalent to 15 grams of carbohydrates
  • Examples of one carb choice include 1 slice of bread, 1/3 cup of cooked pasta or rice, 1 small fruit, or 1 cup of milk
• Patients learn to read food labels and use carbohydrate counting tools (food lists, apps) to determine the carbohydrate content of meals and snacks
• Insulin-to-carbohydrate ratios (I:C) and insulin sensitivity factors (ISF) are used to calculate mealtime insulin doses based on the amount of carbohydrates consumed and the patient's blood glucose level
  • I:C ratio represents the number of grams of carbohydrates covered by one unit of insulin (e.g., 1:10 means one unit of insulin covers 10 grams of carbohydrates)
  • ISF represents the expected drop in blood glucose (mg/dL) per unit of insulin (e.g., 1:50 means one unit of insulin is expected to lower blood glucose by 50 mg/dL)
• The plate method is a simple meal planning approach that emphasizes portion control and balanced nutrition
  • The plate is divided into four sections: 1/2 non-starchy vegetables, 1/4 lean proteins, 1/4 starches or grains, and a side of fruit or low-fat dairy

Exercise and Lifestyle Modifications

• Regular physical activity is an essential component of diabetes management that improves insulin sensitivity, glycemic control, cardiovascular health, and overall well-being
• The American Diabetes Association recommends at least 150 minutes of moderate-intensity aerobic exercise per week, spread over at least three days, with no more than two consecutive days without activity
  • Examples of moderate-intensity activities include brisk walking, cycling, swimming, and dancing
• Resistance training (strength training) should be performed at least twice a week, targeting all major muscle groups
  • Resistance training helps maintain and build muscle mass, improve insulin sensitivity, and support weight management
• Patients should be educated on the effects of exercise on blood glucose levels and how to prevent and treat exercise-related hypoglycemia
  • Adjustments to insulin doses or carbohydrate intake may be necessary before, during, or after exercise, depending on the type, duration, and intensity of the activity
• Lifestyle modifications for diabetes management include maintaining a healthy weight, quitting smoking, managing stress, and getting adequate sleep
  • A 5-7% weight loss can significantly improve glycemic control and reduce the risk of complications in overweight or obese individuals with T2D
  • Smoking cessation reduces the risk of cardiovascular disease, microvascular complications, and premature death in patients with diabetes
  • Stress management techniques (relaxation, mindfulness, deep breathing) can help reduce the negative impact of stress on blood glucose levels and overall health
  • Adequate sleep (7-9 hours per night for adults) is essential for maintaining insulin sensitivity, regulating appetite, and supporting overall health and well-being

Medications and Insulin Therapy

• Pharmacological therapy is often necessary to achieve and maintain glycemic control in patients with diabetes, in addition to lifestyle modifications
• Metformin is the first-line oral medication for T2D, as it reduces hepatic glucose production, improves insulin sensitivity, and has a low risk of hypoglycemia
  • Other oral medications for T2D include sulfonylureas, thiazolidinediones, DPP-4 inhibitors, SGLT2 inhibitors, and GLP-1 receptor agonists
• Insulin therapy is essential for all patients with T1D and may be required for some patients with T2D when oral medications and lifestyle changes are insufficient to achieve glycemic targets
• The main types of insulin are rapid-acting (lispro, aspart, glulisine), short-acting (regular), intermediate-acting (NPH), and long-acting (glargine, detemir, degludec)
  • Insulin regimens can be basal-only (long-acting), basal-bolus (long-acting + rapid-acting at meals), or premixed (combination of short-acting and intermediate-acting)
• Insulin dosing is individualized based on the patient's insulin sensitivity, carbohydrate intake, and glycemic targets
  • Insulin-to-carbohydrate ratios (I:C) and correction factors (CF) are used to calculate mealtime insulin doses based on the patient's blood glucose level and the amount of carbohydrates consumed
• Patients on insulin therapy should be educated on the signs and symptoms of hypoglycemia, how to prevent and treat low blood sugar, and when to seek medical attention
• Continuous subcutaneous insulin infusion (CSII) using an insulin pump can provide more precise insulin delivery and greater flexibility in meal timing and physical activity for some patients with T1D or T2D

Complications and Prevention

• Chronic hyperglycemia can lead to microvascular and macrovascular complications that significantly impact the quality of life and mortality of patients with diabetes
• Microvascular complications affect small blood vessels and include:
  • Retinopathy: damage to the blood vessels in the retina, leading to vision loss or blindness
  • Nephropathy: damage to the kidneys, leading to chronic kidney disease and end-stage renal disease
  • Neuropathy: damage to the nerves, leading to sensory loss, pain, and autonomic dysfunction (gastroparesis, erectile dysfunction, orthostatic hypotension)
• Macrovascular complications affect large blood vessels and include:
  • Cardiovascular disease: increased risk of coronary artery disease, myocardial infarction, and stroke
  • Peripheral artery disease: narrowing of the arteries in the legs, leading to pain, ulcers, and amputation
• Prevention and early detection of complications involve:
  • Maintaining optimal glycemic control (A1C <7% for most patients)
  • Regular screening for retinopathy (dilated eye exam), nephropathy (urine albumin-to-creatinine ratio), and neuropathy (foot exam)
  • Managing cardiovascular risk factors (blood pressure, lipids, smoking cessation)
  • Adopting a healthy lifestyle (balanced diet, regular physical activity, stress management)
• Patient education and self-management support are crucial for preventing complications and improving outcomes
  • Patients should be taught the importance of adhering to their treatment plan, monitoring blood glucose levels, and recognizing the signs and symptoms of complications
• Regular follow-up with a multidisciplinary healthcare team (primary care provider, endocrinologist, registered dietitian, diabetes educator, podiatrist, ophthalmologist) is essential for comprehensive diabetes care and prevention of complications

Special Considerations and Case Studies

• Pregnancy and diabetes:
  • Preconception counseling and optimal glycemic control before and during pregnancy are essential to reduce the risk of congenital anomalies and adverse maternal and fetal outcomes
  • Gestational diabetes mellitus (GDM) requires close monitoring and management to prevent complications such as macrosomia, neonatal hypoglycemia, and increased risk of T2D later in life
• Diabetes in older adults:
  • Glycemic targets may be less stringent (A1C <8%) for older adults with limited life expectancy, multiple comorbidities, or high risk of hypoglycemia
  • Medication regimens should be simplified, and the risk of polypharmacy and drug interactions should be considered
  • Functional status, cognitive function, and social support should be assessed and addressed as part of the comprehensive care plan
• Diabetes and eating disorders:
  • Eating disorders (anorexia nervosa, bulimia nervosa, binge eating disorder) can complicate diabetes management and increase the risk of complications
  • Screening for eating disorders should be part of routine diabetes care, especially for adolescents and young adults
  • Treatment involves a multidisciplinary approach addressing both diabetes management and the underlying eating disorder
• Case study 1: A 45-year-old man with newly diagnosed T2D, BMI 32 kg/m2, A1C 8.5%, and hypertension
  • Initiate metformin and lifestyle modifications (balanced diet, regular physical activity, weight loss)
  • Set glycemic target (A1C <7%) and monitor progress through regular follow-up
  • Address hypertension management and screen for complications
• Case study 2: A 22-year-old woman with T1D, planning pregnancy
  • Provide preconception counseling and optimize glycemic control (A1C <6.5%) before conception
  • Adjust insulin regimen and monitor blood glucose levels closely during pregnancy
  • Ensure regular follow-up with a multidisciplinary team (endocrinologist, obstetrician, registered dietitian) throughout pregnancy and postpartum
• Case study 3: A 70-year-old man with long-standing T2D, multiple comorbidities, and history of severe hypoglycemia
  • Reassess glycemic targets (A1C <8%) and simplify medication regimen to minimize the risk of hypoglycemia
  • Evaluate functional status, cognitive function, and social support
  • Provide education on hypoglycemia prevention and treatment, and involve caregivers in the