New onset diabetes mellitus

Differential Diagnosis

Hyperglycemia

Diabetic Emergencies

• Diabetic ketoacidosis (DKA)
• Diabetic ketoacidosis (peds)
• Hyperosmolar hyperglycemic state (HHS)
• Nonketotic hyperglycemia
• Euglycemic DKA (SGLT-2 inhibitors, pregnancy, fasting)

Diabetes Mellitus (New or Known)

• Type 1 diabetes mellitus (new-onset or uncontrolled)
• Type 2 diabetes mellitus (new-onset or uncontrolled)
• Medication noncompliance or insulin pump malfunction
• Gestational diabetes
• Latent autoimmune diabetes of adults (LADA)

Medication/Drug-Induced

• Corticosteroids (most common drug-induced cause)
• Thiazide diuretics
• Atypical antipsychotics (olanzapine, clozapine, quetiapine)
• Beta-blockers (especially non-selective)
• Phenytoin
• Tacrolimus, cyclosporine (transplant patients)
• Protease inhibitors (HIV antiretrovirals)
• Catecholamines (epinephrine, norepinephrine infusions)
• SGLT-2 inhibitors (paradoxical DKA with euglycemia)
• Total parenteral nutrition (TPN)
• Dextrose-containing IV fluids (iatrogenic)
• Niacin
• Pentamidine (initially hyperglycemia, then hypoglycemia from beta-cell destruction)

Physiologic Stress Response

• Sepsis / critical illness (stress hyperglycemia — very common in the ED)
• Trauma / major surgery / burns
• Acute coronary syndrome / myocardial infarction
• Stroke (especially hemorrhagic)
• Pancreatitis (both a cause and consequence)
• Shock (any etiology)
• Pain (catecholamine surge)
• Seizure (postictal)
• Physiologic stress alone rarely causes glucose >200 mg/dL in non-diabetics; glucose >200 in a "stress response" should prompt evaluation for undiagnosed diabetes or prediabetes

Endocrine

• Cushing syndrome / Cushing disease (cortisol excess)
• Pheochromocytoma (catecholamine excess)
• Hyperthyroidism / thyroid storm
• Acromegaly (growth hormone excess)
• Glucagonoma (rare)
• Somatostatinoma (rare)

Pancreatic

• Pancreatitis (acute or chronic — destruction of islet cells)
• Pancreatic malignancy (adenocarcinoma, neuroendocrine tumors)
• Post-pancreatectomy
• Cystic fibrosis-related diabetes
• Hemochromatosis (iron deposition in pancreas — "bronze diabetes")

Toxic/Overdose

• Iron toxicity (hepatic injury → impaired glucose regulation)
• Salicylate toxicity (can cause both hyper- and hypoglycemia)
• Sympathomimetic toxicity (cocaine, methamphetamine)
• Calcium channel blocker toxicity (impairs insulin secretion)
• Carbon monoxide toxicity (stress response)

Other

• Renal failure (chronic kidney disease, acute kidney injury — impaired insulin clearance AND insulin resistance)
• Cirrhosis / hepatic failure (impaired glycogenolysis regulation)
• Pregnancy (gestational diabetes, steroid administration for fetal lung maturity)
• Parenteral nutrition (TPN, dextrose-containing fluids)
• Post-transplant diabetes (immunosuppressants)

Complications of Diabetes (Not Causes of Hyperglycemia)

These are associated conditions that may be present alongside hyperglycemia but do not themselves cause elevated glucose:

• Diabetic foot infection
• Diabetic peripheral neuropathy
• Cerebral edema in DKA
• Diabetic retinopathy
• Diabetic nephropathy

Treatment

• If HbA1c > 6.5, titrate fasting blood sugar to 80 to 120
• ADA diet control until HbA1c is >7
• 1st line Metformin 500mg BID --> 1000mg BID, do not give in people with abnormal LFT's, CHF Stage 3/4 and ARI, CKD
• 2nd Agent Glipizide start 2.5mg BID -->5mg BID, need to monitor for hypoglycemia
• 3rd Agent Pioglitazone
• After 3 agents need to start insulin if not controlled, ie NPH BID or Lantus Qday (0.5mg/kg) and titrate to Fasting Blood Sugar
• all DM need HbA1c q 3mo, Ma-cr to check for microalbuminuria q year

See Also

• Diabetes Mellitus (Main)