Postprandial blood glucose latency after oatmeal is a valid screening test for diabetic gastropathy in type 1 diabetes, but not in type 2 diabetes.

Disordered gastric motility occurs frequently in diabetes mellitus. Gastric emptying time is abnormal in about 50% of diabetic patients and delayed emptying time is known as an important cause for brittle diabetes in type 1 diabetes. We compared the rise in blood glucose after a standardized meal (oatmeal test) as a noninvasive screening test for diabetic gastropathy with the noninvasive measurement of gastric emptying time with ultrasound in type 1 and type 2 diabetic patients. The test result was considered pathological if the rise of blood glucose after an initial steady state did not reach 20 mg/dl in the first 20 min after the meal (prolonged blood glucose latency). We found a sensitivity of 90% (58.7-99.8) and a specificity of 100% (71.5-100) for the oatmeal test in type 1 diabetes in the gastropathy screening. In type 2 diabetes we found a sensitivity of 13% (1.5-38.3) and a specificity of 78% (60-90.7) (95% CI). In conclusion, the oatmeal test seemed to be a good, noninvasive screening test in diabetic gastropathy in type 1 diabetes, but has no diagnostic value in type 2 diabetes. The causes for such a difference may be due to a different postprandial blood glucose regulation in type 2 diabetes compared to the beta-cell-depleted type 1 diabetes.