Type 2 Diabetes among Asian Indian Men with Transient versus Persistent Impaired Glucose Tolerance

Arun Raghavan1, Arun Nanditha1,Ramachandran Vinitha1,Mary Simon1, Sundaram Selvam1,Priscilla Susairaj1,Krishnamoorthy Satheesh1,  Jagannathan Ram2,Chamukuttan Snehalatha1,Ian F Godsland3,Desmond G Johnston3, Ambady Ramachandran1

1India Diabetes Research Foundation and Dr. A. Ramachandran's Diabetes Hospitals,
Chennai, India

2Hubert Department of Global Health, Emory Global Diabetes Research Center, Atlanta, USA

3Faculty of Medicine, Imperial College, London, UK    

Background: 
Asian Indians have high rates of impaired glucose tolerance (IGT) and many of them rapidly convert to type 2 diabetes (T2D).  During the selection of persons with IGT for a diabetes prevention study, men aged 35 to 55 years with risk factors for T2D were requested to undergo standard oral glucose tolerance test (OGTT).  Persons with IGT were invited to repeat the test within a week. The presence of two positive tests was termed persistent IGT (PIGT).  A positive result only on the first test was termed having transient IGT (TIGT).  

Aim: 
The aim of the study was to compare the incidence of T2D among the two groups of men over a 5 year period.

Methods: 
The study samples were from participants who underwent the clinical screening for a randomized controlled diabetes prevention study started in 20091.  Persons with PIGT (n=236) and with TIGT (n=569) underwent a follow up OGTT 5 years later.  Participants with TIGT were given standard advice on lifestyle modification only at the time of initial screening.  They were invited for a repeat clinical assessment after a median period of 5 years (Aug-Dec 2015). For PIGT, only persons randomized in the control arm of the prevention trial (standard lifestyle advice) were invited for the final assessment at 5th year.   During the active phase of the study, persons with PIGT underwent 6 monthly clinical and biochemical reviews for 2 years and they were later retested at the end of 5 years. Comparison of incidence of diabetes between the two study groups were done using Cox’s regression analysis.

Results: 
Conversion to diabetes occurred among 78 of TIGT persons (13.7%) and among 106(44.9%) in the PIGT group in 5 years. The conversion rate to diabetes was significantly lower among people who had TIGT when compared with people with PIGT, as shown by Cox’s regression analysis (HR=0.241, CI(0.179-0.323)p<0.0001).

Discussion: 
PIGT was associated with a high conversion to diabetes, whereas the conversion rate was significantly lower in persons who had TIGT. This reinforces the fact that a repeat blood test is mandatory to confirm and classify subjects as IGT or Prediabetes. Institution of a healthy lifestyle by dietary modification and enhanced physical activity helps to prevent diabetes in such people2-4. The initial prevention study showed that there was a relative risk reduction of 36% in incident diabetes among the intervention arm who practiced lifestyle modification over 2 years. This report gives evidence that those subjects with IGT confirmed by a second blood test namely, PIGT, have higher risk and will benefit from intervention to prevent conversion to T2D. 

References:
1.Ramachandran A, Snehalatha C, Ram J, Selvam S, Simon M, Nanditha A et al. Effectiveness of mobile phone messaging in prevention of type 2 diabetes by lifestyle modification in men in India: a prospective, parallel-group, randomized controlled trial. Lancet Diabetes Endocrinol. 2013;1(3):191-198.
2.Knowler WC, Barrett-Connor E, Fowler SE, Hamman RF, Lachin JM, Walker EA et al. Diabetes Prevention Program Research Group. Reduction in the incidence of type 2 diabetes with lifestyle intervention or metformin. N Engl J Med 2002;346(6):393–403. 
3.Tuomilehto J, Lindström J, Eriksson JG, Valle TT, Hämäläinen H, Ilanne-Parikka P et al. Finnish Diabetes Prevention Study Group.  Prevention of type 2 diabetes mellitus by changes in lifestyle among subjects with impaired glucose tolerance. N Engl J Med 2001;344(18):1343-1350. 
4.Pan XR, Li GW, Hu YH, Wang JX, Yang WY, An ZX et al. Effects of diet and exercise in preventing NIDDM in people with impaired glucose tolerance: The Da Qing IGT and diabetes study. Diabetes Care 1997;20(4): 537–544.

Incidence of type 2 diabetes among Asian Indian men with transient versus persistent impaired glucose tolerance