Fast decline in insulin sensitivity seen in pre-diabetic South Asians

Sep 18 2014

By Sara Freeman, medwireNews Reporter

People of south Asian descent who have Type 2 diabetes show a more rapid decline in fasting glucose levels than White individuals even before they develop the disease, new findings from the Whitehall II study suggest.

Fasting plasma glucose (FPG) was an average of 0.34 mmol/L per decade higher in south Asians than in White patients before a diabetes diagnosis, and 0.36 mmol/L per decade higher at diagnosis.

Whitehall II was a study of more than 10,000 British civil servants who were aged between 35 to 55 years at recruitment. Participants were sent health questionnaires and underwent regular health assessments, which included anthropometric, blood pressure, blood glucose, lipid and serum insulin measurements every 5 years.

A total of 95 south Asian and 724 White participants were included in the current analysis, which had a total of 17 years of follow-up.

Previous findings from the study showed glucose tolerance declined more rapidly with age in south Asians – defined as those of Indian, Pakistani and Bangladeshi origin – than in Europeans. The reason for this difference was thought to be due to the lack of a mechanism to compensate for declining insulin sensitivity in south Asians that exists in their White counterparts.

Thus the aim of the present investigation was to investigate this phenomenon further, looking at fasting and postload glucose levels and changes in insulin sensitivity and beta-cell function before diabetes was diagnosed.

The diagnosis of Type 2 diabetes was made on the basis of an oral glucose tolerance test (OGTT), oral antidiabetic drug (OAD) use and self-reports.

Two-hour postload glucose curves were similar for south Asian and White patients. This was unexpected, study investigator Adam Tabák, of University College London, said while presenting the findings at the 2014 annual meeting of the European Association for the Study of Diabetes, held in Vienna, Austria.

Trajectories of insulin sensitivity before a diabetes diagnosis showed a more rapid decline in south Asian patients than in White patients. Although insulin secretion increased in both ethnicities until 7 years before diagnosis, the rise was more rapid in White patients and decreased thereafter until a diagnosis was made.

“It is a well known fact that south Asians have an increased risk of Type 2 diabetes,” Tabák observed.

“We confirm an increased risk and earlier onset of Type 2 diabetes among south Asians.”

Tabák commented that “earlier detection may be possible” and that there may be a “longer window of opportunity for preventative efforts” in this patient population.

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