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GLUCOSE HOMEOSTASIS: DIABETES MELLITUS
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A heterogeneous group of disorders characterized by fasting and postprandial hyperglycemia that affects approximately 2.5 per 1000 children under 20 years of age.
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Type 1 DM: Onset is usually in childhood, but may occur at any age; accounts for 85% of diabetes cases in children.
Type 2 DM: Most prevalent in obese children during puberty; more frequent in children who identify as African American, Hispanic, Pacific Islander, Asian, and Pima Indian; accounts for 12% of diabetes cases in children.
MODY: Autosomal dominant inheritance; onset usually between 9 and 25 years of age; accounts for 1–2% of diabetes cases in children.
Neonatal diabetes: De novo or inherited; onset usually <6 months of age; accounts for 1% of diabetes cases in children.
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Type 1 DM: Autoimmune-mediated destruction of β cells in predisposed individuals (certain HLA haplotypes), trigger(s) unknown, but thought to be environmental
Type 2 DM: Progressive insulin secretory defect on the background of insulin resistance
MODY: Genetic defects in enzymes or nuclear transcription factors involved in the regula-tion of insulin secretion or pancreatic islet development
Neonatal diabetes: Genetic defects in KATP channel, insulin, or transcription factors involved in the regulation of insulin secretion or in pancreatic-islet development
Other: Pancreatectomy, exocrine pancreatic disease (cystic fibrosis, hemochromatosis); other endocrinopathies (acromegaly, Cushing disease, pheochromocytoma); medications (glucocorticoids, beta-blockers, phenytoin, asparaginase, cyclosporine, tacrolimus, pentamidine, diazoxide, nicotinic acid, thiazides); infections (cytomegalovirus, congenital rubella); genetic syndromes (Prader–Willi, trisomy 21, Turner, Klinefelter)
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Insulin deficiency and/or impaired insulin action results in the abnormal metabolism of carbohydrate, protein, and fat.
Type 1 DM: Destruction of pancreatic β-cells leads to absolute insulin deficiency. Lack of insulin results in excessive hepatic glucose production and impaired glucose utilization in muscle and fat, leading to hyperglycemia, glycosuria, and osmotic diuresis. Lipolysis and impaired lipid synthesis lead to elevated lipids, cholesterol, triglycerides, and free fatty acids, which are converted into ketones. Impaired utilization of glucose, excessive caloric and water losses in urine, and increasing catabolism all lead to weight loss.
Type 2 DM: Insulin resistance and inadequate insulin secretion result in relative insulin deficiency. Most patients have sufficient insulin to suppress lipolysis and ketogenesis, although this is not always the case in the pediatric population where patients do present with ketoacidosis.
MODY: Each of the MODY gene defects result in very unique clinical features spanning mild, not progressive, fasting hyperglycemia to more profound insulin dependent DM. There are also genes that initially cause a hyperinsulinism picture with hypoglycemia in infancy and progress to later diabetes. Monogenic diabete are also often associated with other non-endocrine manifestations such as developmental delay, cardiomyopathy and hepatic dysfunction.
Neonatal Diabetes: Similar to other types of diabetes, these patients present in infancy with polyuria, poor weight gain and high risk of diabetic ketoacidosis. Individuals that have pancreatic aplasia may also present with diarrhea ...