A research study has confirmed that excessive use of synthetic pesticides and insecticides increases the long-term risk of type 2 diabetes. These chemicals adversely alter your gut health, triggering oxidative stress and inflammation. This can set the stage for insulin resistance, leading to diabetes and cardiovascular complications over time.
“Organophosphates are among the biggest threats as far as diabetes is concerned. Unfortunately, this group of pesticides and insecticides are the most widely used ones for agriculture and horticulture crops across the world,” says Dr G Velmurugan, scientist, KMCH Research Foundation, Coimbatore. He adds that farmers are regularly exposed to these chemicals as they handle them with their bare hands and inhale them while spraying. The fruits and vegetables grown using these pesticides pose a serious risk to consumers, leading to several health conditions.
The Food and Agriculture Organization (FAO) of the United Nations has also confirmed organophosphate as a potential risk factor for diabetes in a report released in November 2023, recommending the inclusion of gut health impact as part of the pesticide residue risk assessment.
From Nazi gas chambers to farmlands
Organophosphate-based pesticides have replaced the traditional organochloride-based ones like endosulfan and DDT since the early 70s. The chloride-based pesticides were taken off the shelves as they weren’t biodegradable, leaving traces in the environment and soil. Reacting to this, the chemical industries came up with organophosphate-based pesticides, referring to them as a ‘safer option’ to protect the crops and ensure a bumper harvest for the farmers.
“Organophosphates were the same nerve agents that were perfected by Hitler’s Nazi scientists to be used as chemical weapons. They used to test its efficacy on the inmates at the concentration camps. Though organophosphates are biodegradable compared to endosulfan and DDT, these are still essentially neurotoxic chemicals,” Dr Velmurugan shares.
Pesticides and diabetes: Prevalence among rural population
Dr Krishnan Swaminathan, a Coimbatore-based endocrinologist and a leading researcher on this topic along with Dr Velmurugan, sheds light on the high prevalence of non-communicable diseases (mainly diabetes) and cardiovascular complications among the rural population. “We studied people from various village clusters in Tamil Nadu and found a high prevalence of prediabetes, diabetes and atherosclerosis among the predominantly agrarian community there. Interestingly, these affected people were also relying on organophosphate pesticides to safeguard their crops,” he informs. As many as 3080 participants were involved in the study.
Dr Velmurugan says that organophosphates are generally known to inhibit the enzyme acetylcholinesterase (AChE), which is involved in neurotransmission in both insects and humans. “But surprisingly, we could not find any variations in enzyme levels in the participants. So, we decided to probe deeper to find the diabetic link by checking whether these chemicals had any impact on their gut health,” he adds, pointing out that most participants appeared to be physically fit and healthier than their urban counterparts diagnosed with diabetes.
Dr Swaminathan points out that these pesticides can cause oxidative stress and inflammation, often leading to liver and pancreatic damage. They can also impair the functioning of the adrenal gland, which will lead to hormonal imbalances. All these conditions are risk factors for hyperglycemia (high blood glucose levels).
The gut instinct and gluconeogenesis
In an attempt to fully understand the effects of prolonged organophosphate exposure, the researchers decided to expose a carefully selected batch of lab mice to identical levels of organophosphates daily, similar to the people who were exposed to these chemicals every day. “All previous toxicology studies of these chemicals were done on large doses of exposure. Ours is the first one to replicate day-to-day levels to understand the direct link between pesticides and diabetes,” Dr Velmurugan adds.
As expected, the mice that were given organophosphate-laced water did not show any variation in body weight or acetylcholinesterase levels. However, their blood glucose levels increased, with the average fasting blood glucose levels getting as high as 200 mg/dL. Further analysis revealed that the gut bacteria were at work, and the organophosphates, along with some enzymes, were broken down multiple times. Certain metabolites (byproducts) like acetate were also further broken down into glucose. “This metabolic process is called gluconeogenesis, where glucose is formed from non-carbohydrate sources, mainly lipids and proteins. It’s sort of an emergency response system in our body,” says Dr Velmurugan.
He also points out that they collected fecal samples from the participants that were analyzed and found residues of metabolized organophosphates and enzymes, further confirming their findings on the link between pesticides and diabetes. The study, published in the journal Genome Biology in 2017, was also included in the detailed report on the impact of pesticide residue on human health published by the FAO.
Both Dr Swaminathan and Dr Velmurugan were also part of the 2021 Rural Epidemiology of Diabetes in South India (REDSI) study, which also reported a high prevalence of diabetes in rural South India. This study, however, focused on the diabetes risk element in people from the agrarian sector. Interestingly, age and hypertension were the only traditional risk factors for diabetes in most of these rural people. “However, there was a strong statistical co-relation in all these cases — exposure to organophosphate pesticides on a daily basis for a long time,” Dr Swaminathan adds.
Including gut health in pesticide risk assessment
Based on the overwhelming data derived from rodent models, the latest FAO report has recommended further studies about the impact of pesticides on human gut health. It has categorically stated that pesticide residue could alter the human gut microbiome. Hence, this aspect must be included in the pesticide risk assessment. Dr Velmurugan says that besides reducing the usage of harmful pesticides, people should try to buy vegetables and fruits that are grown organically. They should also thoroughly wash and peel off their outer layer before consumption.
Takeaway
Excessive usage of pesticides on agricultural crops has emerged as a risk factor for type 2 diabetes. Organophosphates get broken down into multiple substances in the gut, which are then broken down into glucose through gluconeogenesis. This causes an increase in blood glucose, leading to organophosphate-induced diabetes in the long run.
