Diabetes Mellitus Type 1

Epidemiology

Incidence – increase with age through puberty then declines

Prevalence – 1.2 to 1.9/1000 Geography – common in northern and

southern areas of the world, such as Scandinavia and new Zealand

Underlying pathogenesis?

Insulin deficiency

Causes?

Combination of genetics and environment

Genetic causes

30-50% concordant in identical twins 1/40-80 or 1/20-40 chance of developing diabetes if

mom or dad has diabetes, respectively HLA DR3 or DR 4

3.5-fold increase with either one 10-fold increase with both 95% of type 1 have both

Associated with other autoimmune diseases such Graves’ disease, hypothyroidism, alopecia

Environmental cause

Viral infection, such as parvovirus B19 and mumps, trigger islet cell destruction, which accounts for frequent occurrence of type 1 in spring and fall

Rare causes

Pancreatitis - not common in children except those with familial triglyceride

Defective beta cell genes

Clinical symptoms

Subacute or acute

Subacute presentations?

Malaise Weight loss – breaking down of proteins and

fats to produce energy for the cells, because glucose could not be transported into the cells without insulin

Polyuria Polydipsia Polyphagia Noctural enuresis

Acute presentations?

Associated with diabetic ketoacidosis Nausea and vomiting Abdominal pain due to DKA or appendicitis Dehydration or shock from osmotic diuresis Breathing

Fruity smell Kussmaul’s breathing

Altered mental status

Tests for diagnosis of diabetes mellitus type 1?

Fasting plasma glucose 126 mg/dL on two occasions

Random plasma glucose 200 mg/dL with symptoms

Two hours glucose tolerance test with plasma glucose 200 mg/dL at 2 hour

Distinctions from diabetes mellitus type 2 Thin Weight loss Insulin:serum glucose

High in type 2 Low in type 1

Tests for work-up?

Urinalysis Proteinuria – should get urine microalbumin Glucose does not confirm or rule out diagnosis of

diabetes mellitus Ketones does not confirm or rule out diagnosis of

DKA Hemoglobin A1c Fasting lipid panel

Diagnosis of DKA?

Hyperglycemia Ketones – β-hydroxybutyrate Metabolic acidosis

Work-up of DKA?

Chemistry Glucose Sodium Potassium Magnesium Phosphorus BUN and creatinine

ABG Serum β-hydroxybutyrate

Management

Hydration Correct ketoacidosis Monitor electrolytes Start insulin regimen

Hydration

Deficits 6-8 liters in DKA and 8-10 liters in NKH 5-10% in children

Rate of replacement depends on the severity of shock – ½ fluid deficit + 40% of maintenance + urine loss + other losses (mL/hour)

Start with normal saline solution and switch to ½ normal saline when patient is hemodynamically stable and potassium is added into IV fluid, because potassium is an osmotic solute

Add dextrose to IV fluid once serum glucose drops < 300 mg/dL to prevent rapid decrease in osmolality leading to cerebral edema

Correct ketoacidosis?

Regular insulin bolus After IV fluid bolus to prevent precipitating drop in

glucose 0.1-0.3 unit per kg

Insulin infusion 0.1 unit per kg/hour Adjust insulin rate or IV fluid rate to maintain

serum glucose 200-250 mg/dL

Monitor electrolytes

Glucose Drop after hydration due to increased renal filtration and

decreased insulin resistance due to decreased glucacon, corticoticoids, and catecholamines

Not to lower faster to than 100mg/dL per hour or below 200 – 250 mg/dL acutely because of the risk of cerebral edema

Potassium - drops very quickly after hydration Potassium moves back into the cells due to insulin and

decreased acidosis 0.1 change in pH = 0.6 mEq/L change in potassium in opposite

direction Replace as soon as patient has urine output and no more

hyperkalemia Magnesium and phosphorus – supplement as necessary

Monitor metabolic acidosis

Follow serum bicarbonate and anion gap Not need to do serial ABG Bicarbonate for acidosis

Not routine because CO2 moves into CSF and worsens cerebral pH

Indication pH < 7.1 because of decreased cardiac contractility and

vasodilation impairing tissue perfusion Life-threatening kyperkalemia

Insulin

Start SQ regular insulin 1 hour or NPH 4 hours prior to stopping insulin infusion

Insulin regimen Total 0.5 units/kg/day 2/3 in AM and 1/3 in PM 2/3 NPH and 1/3 regular in AM & 1/2 NPH and 1/2

regular in PM