DoctorSpeak: Don’t let diabetes steal your sight, limb and life

One of the ironies of modern life is how lifestyle diseases develop so insidiously and take hold of our bodies. Type 2 diabetes mellitus (T2DM) is one such disease that, if not diagnosed early and managed, may cost you your sight, limbs, and even life.

I remember a young Punjab politician came to me at the PGI, Chandigarh, over 30 years ago for a routine check-up. Both his eyes had such advanced diabetic eye disease that he could become blind in no time. He had been diabetic for several years, yet no doctor had ever suggested an eye examination. Aggressive laser treatment prevented him from losing sight, but he succumbed to a massive heart attack within a year.

Lifestyle diseases, including T2DM, cancer and cardiovascular conditions, pose a major global challenge and have reached epidemic proportions, especially in India. Dr V Mohan, an internationally renowned diabetologist from Chennai, estimated that in 2000 about 3.2 crore people in India had T2DM. The number increased to 10.1 crore in 2023, marking a threefold increase.

While T2DM was traditionally considered an urban disease of rich and elderly, it is now increasingly affecting younger people, those from low-income backgrounds, and is becoming prevalent in rural areas. In 2024, Dr Sivaprasad from the Centre for Intelligent Healthcare, UK, along with colleagues from several Indian centres, estimated that nearly 2.1 crore people in India suffer from diabetic retinal disease (DRD), while 24 lakh are already blind due to it. They also reported a 2-3 times higher risk of cardiovascular diseases among these individuals. At least 25 per cent will develop foot ulcers in their lifetime, a major cause of below-knee amputations.

Understanding the enemy

Normally, the pancreas releases insulin in response to rising blood sugar levels after meals. It is the key hormone that allows sugar from food to enter cells for energy. However, frequent consumption of refined carbohydrates and crystalline sugars causes repeated sharp surges in the blood glucose, forcing the pancreas to produce excess insulin. Over time, cells in the muscles, liver, and fat tissues become less sensitive to insulin’s action, preventing efficient glucose uptake. As a result, both blood sugar and insulin levels remain persistently elevated, leading to insulin resistance, where cells fail to respond effectively. Inflammation in abdominal fat releases harmful molecules that further impair insulin’s ability to act on cells.

Insulin resistance develops gradually over 10 to 15 years, driven by genetic factors and unhealthy habits such as overeating and/or regular consumption of ultra-processed food, physical inactivity and weight gain. Before the onset of T2DM, most people go through a ‘prediabetes’ phase, during which blood sugar levels may appear normal (fasting blood sugar levels between 100 and 125 mg/dL) because the pancreas compensates by producing more insulin. Eventually, the pancreas becomes exhausted, and its function declines.

The good news is that if insulin resistance is recognised early, lifestyle changes such as a healthy diet, weight loss and regular exercise can significantly improve insulin sensitivity and potentially slow down or even reverse the progression towards diabetes.

Impact on eyes

Persistent high blood sugar levels slowly damage tiny blood vessels (capillaries) throughout the body, especially in the retina. The earliest visible signs are micro-aneurysms, small red dots about 30–100 micrometres in size that can be seen during a routine eye examination. Even a single micro-aneurysm serves as a warning sign of DRD and should prompt a comprehensive check-up for diabetes and related heart issues.

DRD develops gradually and without any pain. There are no symptoms in the beginning, making it more dangerous. Over time, more micro-aneurysms form and start leaking fluid, affecting both reading and distance vision. In advanced stages, abnormal new blood vessels grow in the retina, which can burst and bleed into the eye, leading to sudden, sometimes complete, loss of sight. Although effective treatment can prevent blindness at each stage, timely diagnosis and access to skilled medical care remain significant challenges in India.

Effect on kidneys & leg amputation

Most complications of T2DM usually occur after 10-15 years of its onset and often develop simultaneously. Retinal changes often signal the onset of chronic kidney disease that may eventually require dialysis and transplantation. Every year, an alarming 45,000-100,000 below-the-knee amputations in India happen because of infected ulcers and gangrene caused by poor blood circulation and nerve loss in patients with T2DM, especially at peripheries.

Early and regular screening

Since DRD’s early stage is often asymptomatic, all T2DM patients should undergo regular eye examination after diabetes’ onset. If there is no evidence of DRD, they should go for eye examination every two years. In case of DRD onset, examination should be more frequent. Diabetics should also be screened annually for kidney issues, peripheral neuropathy, foot sensations and anaemia.

Challenges

While effective treatments for T2DM and its complications have been available for many decades; the difficulty lies in persuading people to change their lifestyle and eating habits and undergo regular testing for diabetes. The doctors on their part, too, should make their patients aware about diabetes screening, and diabetic patients about getting tested for DRD.

— The writer is Emeritus Professor, PGI, Chandigarh

Factcheck: Recent studies say approximately 8.98 crore Indian adults (aged 20-79) had diabetes in 2024. Driven by urbanisation, aging population, and lifestyle changes, projections for 2045 indicate 12.4 crore diabetes cases. Multiple studies indicate high prevalence of DRD in India, ranging from 33% to over 72%. The number is projected to rise soon. Major modifiable risk factors associated with the onset and progression of DRD include high HbA1c, high blood pressure and high cholesterol and triglycerides. Awareness, regular eye screenings, adequate self-care and a healthy lifestyle can help check onset and/or progression of DRD.