Can metformin (biguanide oral hypoglycemic) cause nocturnal enuresis?

Metformin and Nocturnal Enuresis

Metformin does not cause nocturnal enuresis as a documented side effect. Based on the available evidence, nocturnal enuresis is not listed among the known adverse effects of metformin therapy.

Known Side Effects of Metformin

• Metformin's primary adverse effects are gastrointestinal in nature, including diarrhea, nausea, vomiting, abdominal discomfort, and flatulence 1
• Reduction in appetite can occur with metformin use, which may be problematic for some patients, especially older adults 1
• Vitamin B12 deficiency can develop with long-term metformin use, potentially worsening symptoms of neuropathy in patients with type 2 diabetes 1
• Lactic acidosis is a rare but serious complication that can occur with metformin, particularly in patients with renal impairment (CrCl <30 mL/min) 2

Nocturnal Enuresis - Causes and Treatments

• Nocturnal enuresis is commonly associated with nocturnal polyuria (excessive urine production at night), which is typically treated with desmopressin, an antidiuretic vasopressin analogue 2
• Approximately 30% of children with enuresis are full responders to desmopressin and 40% have a partial response 2
• Nocturnal polyuria in enuresis patients appears to be due to a marked nocturnal reduction in renal sensitivity to the antidiuretic effect of vasopressin, rather than medication side effects 3
• Other medications that have been studied for nocturnal enuresis include indomethacin, diazepam, and anticholinergics, but none are as established as desmopressin 4

Management Considerations

• If a patient on metformin develops nocturnal enuresis, consider other potential causes:
  • Nocturnal polyuria due to physiological factors 2
  • Detrusor instability, which is present in approximately 50% of adults with primary nocturnal enuresis 5
  • Bladder hypocompliance, found in about 40% of adults with primary nocturnal enuresis 5
• For patients experiencing nocturnal enuresis while on metformin:
  • Evaluate for other potential causes of enuresis rather than assuming it's medication-related 2, 5
  • Consider standard treatments for nocturnal enuresis such as desmopressin if appropriate 2
  • Implement behavioral modifications such as limiting evening fluid intake and ensuring regular daytime voiding 2

Clinical Pearls

• Metformin should be avoided in patients with CrCl <30 mL/min due to risk of lactic acidosis, but this is unrelated to enuresis 2
• When prescribing metformin, focus on monitoring for its known side effects (GI disturbances, vitamin B12 deficiency) rather than nocturnal enuresis 1
• If a patient on metformin develops nocturnal enuresis, a thorough evaluation for other causes should be conducted, as the condition is unlikely to be related to metformin use 2, 5