9.2 Diabetes Management & Ketogenic Diet Therapy

Type 1 Diabetes: Carbohydrate Counting and Insulin Dosing

Carbohydrate counting is the core nutrition skill for children with type 1 diabetes (T1D). Mealtime (bolus) insulin is matched to carbohydrate using an insulin-to-carbohydrate ratio (ICR) — for example, 1 unit of rapid-acting insulin per 15 g of carbohydrate — and elevated glucose is corrected with a correction factor (insulin sensitivity factor), such as 1 unit lowering glucose by about 50 mg/dL. Protein and fat have smaller, delayed effects that matter mainly for high-fat meals on pump therapy. There are no forbidden foods in T1D; what matters is carbohydrate awareness, portion consistency, and matching insulin to intake. Consistent carbohydrate intake suits children on fixed insulin regimens; flexible counting suits those on basal-bolus or pump therapy.

Sick-Day Management

Illness raises glucose through stress hormones even when the child is not eating. The cardinal rule is NEVER stop basal insulin — insulin omission during illness is the most common pathway to diabetic ketoacidosis (DKA). When the child cannot eat normally, offer carbohydrate-containing fluids at about 15 g per hour (small sips of juice, regular soda, sports drinks, or electrolyte solutions with carbohydrate) to match basal insulin needs, check blood glucose and ketones frequently, and give correction insulin per the sick-day plan. This exact scenario — a vomiting child with T1D — is a classic exam question.

Hypoglycemia: The Rule of 15

Treat glucose below 70 mg/dL with 15 g of fast-acting carbohydrate (4 oz juice or regular soda, 3–4 glucose tablets), wait 15 minutes, recheck, and repeat if still below target. Follow with a snack containing protein or complex carbohydrate if the next meal is more than an hour away. Severe hypoglycemia with inability to swallow requires glucagon.

Diabetic Ketoacidosis (DKA)

Absolute insulin deficiency drives hyperglycemia, osmotic diuresis with dehydration and electrolyte loss, and unopposed lipolysis producing ketoacids and metabolic acidosis. Acute management is medical: isotonic fluid resuscitation, continuous intravenous insulin, and careful potassium repletion. Nutrition becomes relevant at transition to oral intake: once acidosis resolves and the child tolerates food, begin subcutaneous insulin with basal insulin given before the infusion is stopped (overlap to avoid recurrent ketosis), and resume carbohydrate counting for meals.

Type 2 Diabetes in Youth

Youth-onset type 2 diabetes (T2D) is rising in parallel with pediatric obesity. The TODAY study showed it is more aggressive than adult-onset disease: metformin alone failed to sustain glycemic control in about half of participants, with faster beta-cell decline and earlier complications. Metformin is first-line pharmacotherapy; add insulin at diagnosis if there is ketosis, marked hyperglycemia (HbA1c ≥8.5%), or symptoms. GLP-1 receptor agonists (liraglutide, exenatide extended-release) are approved adjuncts in youth ≥10 years. Intensive family-based lifestyle treatment — the same multicomponent approach used for obesity — is foundational. Screening: test at-risk youth beginning at age 10 years or onset of puberty, whichever comes first, when overweight or obesity is present plus additional risk factors (family history, high-risk ethnicity, maternal gestational diabetes, signs of insulin resistance), repeating at least every 3 years.

MODY and Cystic Fibrosis-Related Diabetes

Maturity-onset diabetes of the young (MODY) is monogenic, autosomal dominant, and non-autoimmune; some forms (GCK-MODY) require no treatment at all, so distinguishing it from T1D prevents unnecessary insulin. Cystic fibrosis-related diabetes (CFRD) is insulinopenic without autoimmune destruction; insulin is the only recommended treatment, and — critically — the high-energy, liberalized-fat CF diet is maintained rather than restricted. CFRD is covered in detail in the pulmonary chapter.

Autoimmune Comorbidity Screening in T1D

Screen for celiac disease (tissue transglutaminase IgA with total IgA) and autoimmune thyroid disease at diagnosis and periodically thereafter. Celiac disease in T1D adds real nutrition complexity: a gluten-free diet must be integrated with carbohydrate counting, and many gluten-free substitute products have a higher glycemic index, more fat, and less fiber than their wheat counterparts — dietitian guidance is essential.

Ketogenic Diet Therapy for Refractory Epilepsy

The classic ketogenic diet uses a 4:1 ratio of fat to (protein + carbohydrate) by weight — about 90% of energy from fat — with a 3:1 ratio often used for infants and adolescents to improve tolerance and protein adequacy. It is indicated for drug-resistant epilepsy (failure of at least two appropriate antiseizure medications). Efficacy is well documented: about 50% of children achieve greater than 50% seizure reduction, and roughly 10–15% become seizure-free.

Initiation traditionally required hospital admission with a 24–48 hour fast; non-fasting, gradual-ratio starts achieve equivalent efficacy with better tolerability, and some programs initiate outpatient in stable children. During initiation, monitor blood glucose (hypoglycemia risk) and ketones — beta-hydroxybutyrate (BOHB) blood testing is more precise than urine ketones.

Side effects include constipation (most common), acidosis, hypoglycemia, dyslipidemia, kidney stones (risk amplified by topiramate or zonisamide), growth slowing, reduced bone mineral density, and carnitine deficiency. Supplementation is mandatory: a carbohydrate-free multivitamin with minerals, calcium, and vitamin D; carnitine if levels are low or symptoms develop. Less restrictive alternatives — the modified Atkins diet and the low glycemic index treatment — can be started outpatient and suit adolescents and families unable to manage the classic diet. The dietitian is central: calculating the prescription, training families to weigh foods to the gram, monitoring growth and labs, and adjusting the ratio.

Comparing Ketogenic Diet Variants