Fructose tolerance test in obese people with and without type 2 diabetes

Fructose is distinct among common sugars in its ability to raise serum uric acid, and some studies suggest fructose-induced uric acid production may have a role in the ability of this sugar to induce metabolic syndrome. A fructose tolerance test has been previously developed to evaluate the relative ability of fructose to raise uric acid in individuals. However, the effect of fructose to raise uric acid in people with diabetes has not been studied.

People with type 2 diabetes (n = 143) and without diabetes controls (n = 132) with similar body mass index (BMI) underwent an oral fructose tolerance test. As a comparison, participants also had their uric acid levels measured after an oral glucose tolerance test on a different day.

Serum uric acid was lower in people with type 2 diabetes compared to controls with a similar BMI, especially those with poor glucose control (glycosylated hemoglobin [HbA1c] ≥ 8%). Fructose administration raised serum uric acid in both groups, with a lower absolute rise in people with diabetes. People with diabetes with a blunted rise in serum uric acid had higher baseline serum uric acid concentrations and a higher BMI. People without diabetes with a higher BMI also showed a blunted serum uric acid response. Oral glucose administration lowered serum uric acid in both participants, with a greater fall in those with diabetes.

Both the presence of diabetes and obesity blunt the serum uric acid response to fructose ingestion. These data demonstrate altered fructose-dependent urate metabolism in type 2 diabetes.