What are the possible causes of my frequent daytime urination given a hemoglobin A1c of 5.2%, normal renal function, normal thyroid and calcium levels, and long‑term use of losartan, escitalopram, and clonazepam?

Frequent Daytime Urination with Normal A1C and Long-term Losartan Use

Your A1C of 5.2% definitively excludes diabetes as the cause of your frequent urination, and you should pursue evaluation for primary water balance disorders such as diabetes insipidus or primary polydipsia. 1

Why Diabetes is Excluded

• An A1C of 5.2% is well below the diagnostic threshold for diabetes (≥6.5%) and even below the prediabetes range (5.7-6.4%), making diabetes an extremely unlikely cause of your polyuria 2
• While A1C can occasionally be falsely normal in certain hemoglobin variants, recent blood loss, or hemolysis, this is uncommon and your normal renal function makes these scenarios less likely 1
• Your A1C indicates excellent glycemic control with minimal risk of diabetes-related complications 2

Losartan as a Potential Contributor

Losartan itself does not typically cause polyuria or frequent urination as a direct side effect. However, there are important considerations:

• Losartan is an angiotensin receptor blocker (ARB) used for blood pressure control and renal protection, particularly in diabetic nephropathy 3
• While losartan can affect hemoglobin levels (causing mild decreases), this does not relate to urinary frequency 4
• If you were taking losartan combined with hydrochlorothiazide (a diuretic), this would directly cause increased urination, but you mentioned only losartan 5

Recommended Diagnostic Approach

You should undergo a water deprivation test to differentiate between central diabetes insipidus, nephrogenic diabetes insipidus, and primary polydipsia. 1

Step 1: Initial Urine Testing

• Measure spot urine osmolality to determine if you have water diuresis (<150 mOsm/L) or osmotic diuresis (>300 mOsm/L) 1
• If urine osmolality is <150 mOsm/L, this indicates water diuresis and necessitates a water deprivation test 1

Step 2: Additional Diabetes Exclusion (if osmotic diuresis)

• If urine osmolality is >300 mOsm/L, check fasting plasma glucose and 2-hour oral glucose tolerance test to completely exclude diabetes, despite your normal A1C 1
• This is important because A1C can miss certain patterns of glucose dysregulation 1

Medication Review Considerations

Review your complete medication list with your physician, particularly:

• Confirm whether your losartan formulation contains hydrochlorothiazide (often combined as losartan/HCTZ), which would explain urinary frequency 5
• Escitalopram and clonazepam are not typically associated with polyuria, but medication interactions should be reviewed
• Consider whether any over-the-counter medications or supplements could contribute to increased urination

Critical Safety Warning

If diabetes insipidus is diagnosed and desmopressin treatment is initiated, you must have serum sodium checked within 7 days, at 1 month, and periodically thereafter to prevent life-threatening hyponatremia. 1 This carries a boxed FDA warning due to risk of seizures, coma, respiratory arrest, or death from severe hyponatremia 1

What This Means for Your Cardiovascular Risk

• Your A1C of 5.2% places you at very low risk for developing diabetes (annualized incidence <0.1%) 6
• Continue monitoring other cardiovascular risk factors such as blood pressure control on losartan, cholesterol levels, and smoking status 7
• Your long-term losartan use suggests you likely have hypertension or are receiving renal protection; ensure blood pressure targets are being met 3