Lean diabetes: reality that needs further research, says study

A recent article in Diabetes Care has argued that diabetics who have a low BMI have a unique metabolic profile compared to other groups of diabetics.

Diabetics who have a low body mass index (BMI) have a unique metabolic profile compared to other groups of diabetics, and could be a distinct entity warranting further investigation, a  recent article in Diabetes Care has argued. 

The study looked at the metabolic factors in subjects who were recruited at the Christian Medical College (CMC), Vellore, against control groups comprising individuals with Type 1 and Type 2 diabetes, and similar BMI subjects without diabetes. It was conducted with the Global Diabetes Institute, Albert Einstein College of Medicine, U.S. 

“Diabetes among individuals with low BMI has been recognised for over 60 years as an entity in low and middle income countries (LMIC), and classified as malnutrition-related diabetes mellitus, by the WHO,” says Nihal Thomas, co-author, and head of the department of Endocrinology, Diabetes and Metabolism, CMC Vellore. The need to establish low BMI (or lean) diabetes (LD) as a distinct form of diabetes, and thereby seek attention for it, arose because the WHO withdrew this category in 1999 due to lack of substantial evidence, he adds. 

People with this form of diabetes have a history of malnutrition in utero and continue to have a low BMI into adulthood. The thrifty phenotype theory in diabetes posits that the phenotype (or the observable physical characteristics of an organism, which basically includes the genes, and the impact on them by enviornmental factors) adapts in the womb to poor nutrition. When nutrition improves after birth, this thrifty phenotype becomes disadvantageous to the individual, explains Riddhi Dasgupta, a co author, and endocrinologist.  

Meredith Hawkins, corresponding author of the paper, from the Albert Einstein College of Medicine, New York, further explains: In individuals whose nutritional status improves after birth, it is likely they might seem thin by Western standards, but, in reality, because of the programming in utero, they have actually accumulated more fat than planned for by the gene, leading to the ‘thin-fat’ phenomenon. However, LD individuals never catch up with nutritional requirements, continuing to remain nutritionally challenged as adults, so the thrifty gene never comes into play. It is estimated that there are about 80 million people across the world living with this condition, but since it does not manifest in other than LMIC countries, there is very little research on the subject, she adds. 

 The results of the study demonstrate that the cardinal feature of LD is a defect in insulin secretion capacity versus insulin resistance, as was previously suggested. The subjects were grossly malnourished, the sugar control was poor and their sense of well-being was poor. Given their poor health-seeking behaviour, it would be important to spread awareness among general practitioners to suspect LD among such patients, primarily from rural areas in the country, says Dr. Thomas. If diagnosed wrongly as Type 1 diabetes, physicians might recommend insulin therapy, which may help, but the study has proved that 75 % of the cases could be managed with oral drugs. 

Mini Joseph, dietetics researcher on the study, says protein deficiency is most pronounced in the study group, giving rise to the question whether a protein stimulus might help the patients. In addition, targeting better maternal nutrition would be the way ahead, as it would help avoid several related health and developmental sequelae later in the life of the foetus.