Obesity is common in type 2 diabetes but is rarely seen in autoimmune type 1 diabetes (1). However, as shown in the Diabetes Control and Complications Trial cohort (2,3), a subset of type 1 diabetic patients are overweight, and it has been suggested that intensive insulin therapy may unmask the central obesity or metabolic syndrome in susceptible individuals.

Gastric bypass is considered a gold standard procedure in the surgical treatment of severe obesity, with >50% of excess weight loss occurring within 2 years after the surgery. The weight reduction is maintained over the following years in a vast majority of patients (4). Numerous reports have been published on the beneficial effects of obesity surgery on glucose control and metabolic disorders in impaired glucose tolerant and type 2 diabetic subjects, with an impressive 70–90% of diabetic patients remaining euglycemic without diabetes medications several years after the surgery (5,6). This significant impact of gastric bypass surgery on glucose control is thought to not only result from significant weight loss but also from the exclusion of hormonally active foregut (7,8). It is worth noting that in recent years, gastric bypass has become an increasingly safe procedure (9).

We performed gastric bypass operations in two young women with autoimmune type 1 diabetes associated with severe obesity. Both patients had been obese for many years and were unsuccessful in their previous multiple attempts at losing weight. Having been informed about the benefits and risks of the surgery, they gave their consent to have bariatric surgery performed.

The first patient was a 23-year-old woman with type 1 diabetes since age 15 years, which was poorly controlled (HbA1c 9.5%) and treated with a basal bolus insulin regimen (daily insulin dose 68 IU). Her body weight was 113.5 kg, height 171 cm, and BMI 38.8 kg/m2. She was mildly hypertensive and had hypercholesterolemia treated with a low-cholesterol diet. The patient underwent Roux-en-Y gastric bypass surgery, as described before (9), in August 2000. The surgery and postoperative period were uneventful. Six months after the surgery, her body weight was 84.3 kg (BMI 28.8 kg/m2; 25.7% reduction). After 1 year, it was 77.7 kg (BMI 26.6 kg/m2; 31.5% reduction). However, 2 years after the surgery, her weight increased to 85.0 kg (BMI 29.1 kg/m2) and has remained stable ever since. Eventually, the patient lost 28.5 kg, i.e., 25% of her initial body weight. Her glucose control improved markedly (HbA1c 5.7%), with daily insulin dose reduced to 45 IU, and her blood pressure and plasma lipids returned to normal.

The second patient was a 28-year-old woman who was diagnosed with type 1 diabetes when she was 5 years old. She had been obese since childhood, and her body weight, as in the first patient, had been steadily increasing since the diagnosis of diabetes. Upon presentation, her weight was 126 kg, height 165 cm, and BMI 46.3 kg/m2. She had also been diagnosed with hypertension, hypertriglyceridemia, and, more recently, Sjögren’s Syndrome. She was also treated with intensive insulin therapy (120 IU/day); however, her blood glucose control had been extremely poor for >10 years (HbA1c during this period was between 10.4 and 11.8%). Her other medications included enalapril, bisoprolol, and fenofibrate. She had Roux-en-Y gastric bypass successfully performed in November 2002. Her surgery was complicated by bilateral pneumonia. Ten months after the operation, her weight was 84 kg (BMI 30.1 kg/m2; 33% reduction) and, similar to the previous patient, increased slightly 18 months after the surgery to 89.5 kg (BMI 32.9 kg/m2; 29% reduction). Her metabolic control has improved substantially (HbA1c 7.3%), and her daily insulin dose is now 70 IU. In addition, she no longer requires any treatment for hypertension or lipid disorders and her blood pressure and plasma triglycerides values are now normal.

Our report is, to the best of our knowledge, the first one describing the effects of obesity surgery in type 1 diabetes. In our opinion, gastric bypass surgery, which is being performed increasingly often (∼100,000 operations in the U.S. annually [10]) in obese individuals, also with type 2 diabetes (48), is a feasible, safe, and effective method of weight reduction in young type 1 diabetic patients with severe obesity and comorbidities leading to metabolic syndrome (e.g., hypertension, hyperlipidemia) (11). In our patients, surgery-induced weight loss was also associated with a decrease in insulin requirement per kilogram of body weight (0.60 to 0.53 IU/kg in the first patient and from 0.95 to 0.83 IU/kg in the second patient). This observation may suggest the presence of clinically significant insulin resistance in severely obese type 1 diabetic subjects (12), which was subsequently reduced once weight loss occurred. Importantly, neither of the patients had any significant hypoglycemic episodes after the surgery, despite considerable reduction in HbA1c level and apparent increase in insulin sensitivity.

In conclusion, gastric bypass surgery not only leads to a significant and maintained weight loss in type 1 diabetic patients, but also results in remarkable improvement in metabolic control (absolute reduction in HbA1c of 3–4%) and concomitant disorders. Interestingly, the need for constant intensive insulin therapy in these patients had no detrimental influence on weight loss as an effect of obesity surgery. Both patients lost 50–60% of their excessive body weight during the follow-up period, which is also the rate reported in nondiabetic subjects (4,5,7).

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