Low Iron and High Blood Sugar in a 55-Year-Old Man: Causes and Evaluation

Concurrent iron deficiency and hyperglycemia in a 55-year-old male warrants systematic investigation, as both conditions share several potential underlying etiologies.

Iron Deficiency: Mechanisms

Reduced Intake/Absorption: Vegetarian/vegan diet without adequate planning; gastric atrophy, H. pylori gastritis, celiac disease, post-bariatric surgery, PPIs/H2 blockers impairing non-heme iron absorption.

Chronic Blood Loss (most common in men): GI malignancy (colon, gastric), angiodysplasia, peptic ulcer disease, NSAID/aspirin-induced gastropathy, hemorrhoids. Occult GI bleeding must be excluded.

Hyperglycemia: Mechanisms

Type 2 Diabetes: Insulin resistance ± β-cell dysfunction. Risk factors: central obesity, sedentary lifestyle, family history, age, ethnicity, metabolic syndrome.

Medication-Induced: Glucocorticoids, thiazides, β-blockers, statins (modest), antipsychotics, calcineurin inhibitors.

Other Endocrinopathies: Cushing's, acromegaly, pheochromocytoma (rare).

Shared/Overlapping Etiologies

• Chronic Kidney Disease: Impaired erythropoietin → anemia; insulin resistance → hyperglycemia.
• Alcohol Use Disorder: Gastritis/blood loss → iron deficiency; pancreatitis, hepatic insulin resistance → hyperglycemia.
• Malignancy: Paraneoplastic syndromes, cachexia, direct organ infiltration.
• Genetic Hemochromatosis (paradoxical): Usually causes iron overload, but phlebotomy-induced deficiency can coexist with diabetes ("bronze diabetes").

Recommended Workup

1. CBC, iron studies (ferritin, TSAT, serum iron, TIBC), CRP (ferritin is acute-phase reactant)
2. HbA1c, fasting glucose, lipid panel, LFTs, renal function
3. Fecal immunochemical test (FIT) × 2–3; if positive → colonoscopy ± EGD
4. Review medications (NSAIDs, aspirin, anticoagulants, PPIs)
5. Assess alcohol intake, dietary history, weight trajectory

Early identification of GI malignancy or reversible causes (medication adjustment, dietary modification, alcohol cessation) significantly impacts outcomes.