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Bitesize evidence - Treating prediabetes does not affect progression

Q Does treatment of postprandial hyperglycemia in patients with early, asymptomatic diabetes delay progression to frank fasting hyperglycemia?

Q Does treatment of postprandial hyperglycemia in patients with early, asymptomatic diabetes delay progression to frank fasting hyperglycemia?


Researchers conducting this US-based study enrolled 219 adults with obesity, a history of gestational diabetes, or a family history of diabetes. The patients did not have a diagnosis of diabetes but had a fasting plasma glucose level between 105mg/dl and 140mg/dl (5.5mmol/l - 7.8 mmol/l) and a two-hour postload of plasma glucose of at least 200 mg/dl (11.1 mmol/l).

After a two-day admission for extensive testing, patients were randomly assigned, concealed allocation uncertain, to receive either placebo or acarbose titrated to a maximum dose of 100mg three times daily.

The maximum dose was achieved by 91% of patients. The patients had their fasting glucose level measured every three months for up to five years.

Approximately 43% of the patients did not complete the study. Since the dropout rates were similar in both groups, it is likely that the patients represent a highly motivated group of people. Additionally, given the frequent side effects of acarbose, patients receiving placebo were probably aware of that fact and may have been more rigorous with non-drug efforts to reduce the risk of diabetes. This increased effort might be responsible for the lower than expected development of diabetes in the placebo-treated patients.

Though postprandial glucose levels were decreased by acarbose, over the five years of the study a similar proportion of patients in both groups developed frank fasting hyperglycemia, approximately 30% in both groups (29% versus 34%).

The study was small and the results would only be significant if the treatment decreased the development of diabetes by half as compared with typical rates of development. The results conflict with the shorter-duration STOP-NIDDM study which found, after an average three years, that 32% of treated patients had diabetes compared with 42% of placebo-treated patients (Lancet 2002;359:2072-7). A nonsignificant difference in diabetes also occurred at three years in the current study, although the difference was lost by the end of the study.

Level of evidence

1b- Individual randomised controlled trials (with a wide confidence interval)


Kirkman MS, Shankar RR, Shankar S. Treating postprandial hyperglycemia does not appear to delay progression of early type 2 diabetes. Diabetes Care 2006;29:2095-101.

Bottom Line

The jury is still out regarding the identification and treatment of patients with prediabetes. According to this study, a similar percentage of patients with early diabetes will develop frank diabetes whether or not they receive therapy to lower postprandial glucose levels. A larger, though shorter, study has shown a difference, but it looks like early benefit is lost over time.

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