Body fat distribution, serum glucose, lipid and insulin response to meals in Alstrom syndrome

Background Alstrom syndrome is an autosomal recessive condition characterized by obesity, insulin resistance and hypertriglyceridaemia. Responses to fat and carbohydrate ingestion are important in planning dietetic advice and may help to explain the mechanism of metabolic disorder in the syndrome. Methods After a 12-h fast, five Alstrom subjects received a 3.1 MJ (742 kcal), 75.8% fat breakfast on day 1, and a 3.3 MJ (794 kcal), 77.5% carbohydrate breakfast on day 2. Serum glucose, triglyceride and insulin levels were measured at baseline, and 2 and 3.5 h post-meal. Abdominal computerized tomography in three subjects and magnetic resonance imaging in one demonstrated distribution of abdominal fat. Results Body fat was distributed subcutaneously, as well as viscerally. There were no changes in serum glucose, insulin or triglycerides after the high fat meal. Triglycerides remained stable after the high carbohydrate meal but glucose and log insulin levels increased [8.4 +/- 4.1 to 13.4 +/- 6.9 mmol L-1 (P < 0.05) and 2.6 +/- 0.27 to 3.15 +/- 0.42 pmol L-1 (P < 0.05), respectively]. Conclusions Dietetic advice in Alstrom syndrome must include calorie restriction to reduce obesity, which is predominantly subcutaneous. This study has shown that low carbohydrate advice may prove more effective than fat restriction in control of hyperglycaemia and hyperinsulinism. A single high energy meal does not exacerbate hypertriglyceridaemia.