Issue 174 Item 1 Cry the Fingerstick Away! Blood Glucose Monitors Obsolete

Glucose levels in tears correlate well with blood sugar levels and can be used routinely in monitoring glycemic control.
In a randomized study, Dr. PR Chatterjee and colleagues from the Regional Institute of Ophthalmology, Kolkata, India studied the correlation between blood glucose levels and tear glucose levels in 200 individuals attending their clinic.

Blood glucose levels were estimated quantitatively and also using glucose oxidase strips (Dextrostix). Tear glucose levels were estimated by placing a bent Dextrostix strip in the junction of the inner and middle third of the lower eyelid. Glucose levels in tears of 0 mg/dl, 25 mg/dl, 45 mg/dl, 90 mg/dl, 130 mg/dl, 175 mg/dl > 250 mg/dl were graded 0, 1+, 2+, 3+ , 4+, 5+, 6+ respectively using the Dextrostix strips, the researchers explain. Oral glucose tolerance tests were also carried out in subjects with blood sugar less than 100 milligrams per deciliter (mg/dl).

Blood sugar levels of 130 mg/dl and below, 131-220 mg/dl, 221-310, 311-400 and greater than 400 mg/dl correlated with tear glucose levels of 0, 1+, 2+, 3+, 4+ respectively, Dr. Chatterjee and colleagues report in the August issue of Journal of Association of Physicians of India. Thus, tear glucose levels of less than 25 mg/dl corresponding to grade 0 in the Dextrostix test indicated near normal glucose levels, they note.

Similarly, 91.2% of patients with varying grades of hyperglycemia recorded a positive color response for glucose in tears Dr. Chatterjee’s team reports. Correlation between blood sugar and tear glucose levels were also noted in the patients who were subjected to the glucose tolerance test, the researchers note.

These results are in near agreement with the few studies carried out in the past, the researchers write. The minor variations could be due to the methods used in the estimation of glucose levels, they add.

"The concentration of glucose in tears changes proportionately with the blood glucose level, " Dr. Chatterjee and colleagues explain. "Glycolacria" is a term previously suggested "for the presence of abnormally high concentrations of glucose in tears associated with hyperglycemia," they write.

"The method is very cheap and hence may have a role in community screening programs of diabetes with very little expense," they conclude. J Assoc Phy Ind 2003;101:481-483.

FACT:
Obstructive Sleep Apnea Impairs Insulin Sensitivity in Obesity
Hepatic insulin sensitivity appears to be more impaired in obese patients with obstructive sleep apnea syndrome (OSAS) than in individuals with simple obesity.The effect of OSAS was independent of the degree and distribution of adiposity. Clin Endocrinol 2003;59:374-379.