How to evaluate glucosuria in a 23-year-old female with a body mass index (BMI) of 16, without diabetes mellitus?

From the Guidelines

To evaluate glucosuria in a 23-year-old female with a BMI of 16 who does not have diabetes, I recommend a comprehensive workup focusing on renal tubular dysfunction, starting with a complete urinalysis and blood tests including fasting glucose, HbA1c, renal function panel, and electrolytes, as suggested by recent guidelines 1.

Initial Evaluation

The patient's low BMI and absence of diabetes suggest that the glucosuria may be due to a renal issue rather than a glucose metabolism disorder.

• A complete urinalysis will help identify any other abnormalities in the urine, such as proteinuria or hematuria, which could indicate a more serious renal condition.
• Blood tests, including fasting glucose and HbA1c, will confirm that the patient does not have diabetes, as per the diagnostic criteria outlined in recent studies 1.
• A renal function panel will assess the patient's kidney function and identify any potential issues with electrolyte balance.

Further Testing

Collecting a 24-hour urine sample will provide more information on the patient's glucose excretion and help identify any other substances that may be present in the urine, such as phosphate, amino acids, or proteins.

• A renal tubular function test may be necessary to evaluate the kidney's ability to reabsorb glucose, which could help diagnose conditions such as renal glucosuria or Fanconi syndrome.
• Given the patient's low BMI, it is essential to evaluate for eating disorders and malnutrition, which can affect renal function and contribute to the development of glucosuria.

Potential Diagnoses and Treatment

The most likely diagnosis is renal glucosuria, a benign condition where the kidneys' glucose transporters don't function properly, causing glucose excretion despite normal blood glucose levels.

• Other possibilities include Fanconi syndrome, which involves multiple reabsorption defects, or medication side effects from drugs like SGLT2 inhibitors.
• Treatment depends on the underlying cause, but renal glucosuria itself typically requires no specific treatment beyond monitoring.
• Nutritional support may be necessary given the patient's low BMI, which could be contributing to or resulting from the underlying condition, as emphasized in recent guidelines 1.

From the Research

Evaluating Glucosuria in a 23-year-old Female with BMI 16

To evaluate glucosuria in a 23-year-old female with a BMI of 16 who does not have diabetes, the following steps can be taken:

• The patient's symptoms, signs, and laboratory results should be evaluated to determine if Whipple's triad is present, which includes symptoms and/or signs of hypoglycemia, low plasma glucose, and resolution of symptoms and/or signs after plasma glucose returns to normal 2, 3, 4.
• A detailed history of the patient's symptoms, medications, underlying comorbid conditions, and any acute illness should be obtained 4.
• Laboratory evaluation should be conducted at the time of the spontaneous symptomatic episode, including measurement of plasma glucose, insulin, C-peptide, proinsulin, beta-hydroxybutyrate, and circulating oral hypoglycemic agents 2, 4.
• Supervised tests such as a 72-hour fast or mixed-meal test may be needed to recreate the situation under which the patient is likely to experience symptoms 3, 4.
• The differential diagnosis of hypoglycemic disorder in a seemingly well individual should include drug-induced hypoglycemia, accidental, surreptitious, or malicious hypoglycemia, endogenous hyperinsulinism, and idiopathic postprandial hypoglycemia 3, 4.

Potential Causes of Hypoglycemia

The potential causes of hypoglycemia in this patient include:

• Endogenous hyperinsulinism, such as insulinoma, postbariatric hypoglycemia, and noninsulinoma pancreatogenous hypoglycemia 4.
• Critical illness, hepatic or renal dysfunction, hormonal deficiency, non-diabetes-related medications, and non-islet cell tumors 4.
• Accidental, surreptitious, or malicious hypoglycemia 3, 4.
• Idiopathic postprandial hypoglycemia 3, 4.

Diagnostic Approach

The diagnostic approach to spontaneous hypoglycemia in adults without diabetes mellitus should include:

• Confirmation of hypoglycemia using Whipple's triad 2, 3, 4.
• Detailed history and physical examination 4.
• Laboratory evaluation, including measurement of plasma glucose, insulin, C-peptide, proinsulin, beta-hydroxybutyrate, and circulating oral hypoglycemic agents 2, 4.
• Supervised tests such as a 72-hour fast or mixed-meal test 3, 4.