Urine glucose testing

Urine glucose measurements can be helpful, but it should be remembered that dipsticks have a relatively low accuracy in dogs, often underestimating UG.40 Also, UG concentration is only a reflection of the average BG over the time interval the bladder was filling. Relying solely on UG measurements is not recommended.

Regardless, UG concentration can aid in assessment of a patient when other data conflict. Also, regular determination of UG concentration (at least weekly) can help in assessment of ongoing DM control (see the “Interpreting Urine Glucose Measurements” table below). Consistently negative UG readings may indicate that insulin dosages are excessive. However, a negative UG reading only means that BG was below the renal threshold (i.e., BG could have been 150 mg/dL or 40 mg/dL). The only way to know is to measure BG.41 Lastly, especially for cats for whom stress hyperglycemia prevents obtaining an accurate BGC, UG measurements can be used to adjust the insulin dose. However, such an approach is a last resort because of the potential for causing hypoglycemia. Although far from ideal, there are scenarios where this is the most practical monitoring scheme. Table 3 lists the suggested protocol for using UG test strip readings in cats is based on the Task Force’s clinical experience.

Interpreting urine glucose measurements

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No color change (Negative for glucose)

Remarks

There should be concern that the insulin dose is too high.

Suggested Action

If the reading stays negative, reduce dose of insulin and recheck in 2–3 days.

NOTE: Negative UG in the absence of BGC results could potentially become a dangerous hypoglycemic condition and should be monitored accordingly.

First level color change (100 mg/dL)

Remarks

Ideally, the UG would stay between negative and 100 mg/dL.

Suggested Action

No change in insulin dose, but need to monitor weekly for any changes

Second and third level color change (250 and 500 mg/dL)

Remarks

In the Task Force’s opinion, this is the hardest level to evaluate without a corresponding BG test.

Suggested Action

Consider any dietary changes or deviations (“cheats”). If none are noted, and the cat is not exhibiting clinical signs, recheck daily for 2–3 days.

If the owner is willing, obtaining additional BG data at this time would be ideal depending on the presence or absence of clinical signs. However, if the owner refuses to perform blood work, consider increasing the insulin dosage by half a unit q 12 hr at this time.

Third, fourth, and fifth level change (1,000–2,000+ mg/dL)

Remarks

Cat should have clinical signs at this point

Suggested Action

Increase insulin by 1 unit q 12 hr and recheck in 5–7 days.

NOTE: Continuing to increase the insulin dose more than two or three times is not recommended due to the possible presence of Somogyi or insulin resistance.

Abbreviations: BG, blood glucose; BGC, blood glucose curve; UG, urine glucose.

These guidelines are supported by a generous educational grant from
Boehringer Ingelheim Animal Health USA Inc., and Merck Animal Health.