Efeitos adversos quando da realização do teste de tolerância oral à glicose em pacientes submetidos à cirurgia bariátrica

Abstract

The oral glucose tolerance test (OGTT) is one of the methods used to diagnose type 2 diabetes mellitus and gestational diabetes, and is the World Health Organizations method of choice. The OGTT is frequently requested after bariatric surgery, both for the re-assessment of the diabetes condition in patients who presented altered glycemia before the surgery and also for the triage of gestational diabetes. It is also used in the investigation of other conditions less frequent in the post operatory period, such as hypoglycemia. The OGTT is usually well tolerated and there are no formal contraindications to its performance. The most common collateral effects are nausea and vomit. Several studies describe the occurrence of undesirable symptoms after the intake of carbohydrate-rich food in patients submitted to Roux-en-Y gastric bypass. In most cases, these symptoms were related either to the dumping syndrome, characterized by vasomotor symptoms, profuse sweating, weakness and flushing or to hypoglycemia episodes. However, there are few descriptions of undesirable manifestations during the OGTT, a test that offers a very high level of carbohydrates, in this group of patients. Obesity has been increasing epidemically worldwide. The high prevalence of severe forms of obesity morbid obesity has caused a parallel increase on the surgical treatment of this condition: bariatric surgery. Bariatric surgery is indicated for patients with BMI 40 kg/m² or with BMI 35 kg/m² associated to high-risk co-morbidities, such as cardiopulmonary problems and uncontrolled type 2 diabetes mellitus. Morbid obesity affects 3% of the Brazilian population and the number of candidates to the surgical treatment of obesity is significant. In Brazil, between 2003 and 2010, the number of bariatric surgeries increased from 16,000 procedures to 60,000. Assessment of the glycemic state, either in patients who had diabetes before the surgery or who got pregnant during the post-operatory period, is a frequent reason for the solicitation of the OGTT in clinical pathology laboratories. The present study assessed collateral effects in 128 patients who had had bariatric surgery and had performed the OGTT. One hundred and seventeen (91.4%) were women, 38 (29.7%) were pregnant, the average age was 39 ± 11.8 years, with a BMI median of 30.4 kg/m2. The median time of post-bariatric surgery was 53 months. The main symptoms observed during the performance of the OGTT were: nausea (38.3%), dizziness (30.5%), weakness (25.8%) and diarrhea (23.4%). The main adverse signs detected were: tachycardia (14.1%), tremor (13.4%) and profuse sweating (12.5%). Symptomatic hypoglycemia occurred in 14.8% of the patients and one patient presented glycemia= 24 mg/dL during the test. The presence of adverse signs was associated to hypoglycemia (OR=8.14, CI95% 2.63-25.12). The diagnosis of arterial hypertension represented a higher risk to the incidence of adverse signs (OR=3.64, CI95% 1.17-11.34), after the adjustment for gender, age time of post-operatory and hypoglycemia. The fasting glucose below 75 mg/dl at the beginning of the test was a predicting factor for hypoglycemia during the OGTT (OR= 9.5, CI 95% 2.57-35.11), after the adjustment for gender, age, time of post-operatory and arterial hypertension. The study concluded that patients submitted to bariatric surgery who performed the OGTT presented high incidence of collateral effects. Such effects are not seen in non-operated patients, and some of them are potentially severe, such as symptomatic hypoglycemia. Furthermore, the observed manifestations lead to insecurity and embarrassment of the patients 11 during the test, which justifies medical supervision and appropriate area and equipments to perform the test. Due to the potential risks of the OGTT, we suggest the need of revision, by the assistant physicians, of the reasons for requesting the test in a population with specific characteristics, such as the patients submitted to bariatric surgery.