What’s the link between kidneys and heart health in diabetes?

A 56-year-old man from Bihar visited our hospital and said that his physician had told him that all his reports were okay. His creatinine was 1.52 mg/d (upper limit 1.4 mg/dl), considered him to be slightly off (“almost normal”). I calculated the accurate state of kidney function (eGFR, analysed from a formula) and told him to be careful since his kidney function had already declined 25 per cent. Underestimation or ignorance of kidney damage is common in patients and even some physicians.
The second common misconception is that kidney damage is due to anti-diabetes drugs. A 62-year-old woman complained to me, “The drug Metformin, which you had given, has damaged my kidneys.” Another patient from Agra told me, “You are giving me Dapagliflozin, it excretes sugar in urine, and I will have kidney damage and cancer soon.” Both are wrong. Both these drugs, especially the latter, protect kidneys. Only when kidneys are moderately damaged does Metformin need to be stopped due to occurrence of other side effects.
Kidney dysfunction is not an isolated fallout of diabetes. It is closely linked to heart disease. Even a slight increase of albumin in urine (“microalbuminuria”) increases your heart attack risk several times. Therefore, even a slight damage to the kidney must be dealt with immediately. There are several ways to do it.

First, blood sugar control must be good, not only for a short while but persently for a long period of time. High blood sugar does not damage kidneys overnight but surreptitiously and slowly. Patients need to focus on lifestyle, exercise and regular drug intake to achieve it. Some anti-diabetes drugs are better than others in protecting kidneys. Long-term studies have shown that drugs called SGLT2 inhibitors (Canagliflozin, Dapagliflozin and Empagliflozin) repair kidney damage and reduce the need for dialysis. These drugs become absolutely essential for those who have definite kidney disease.
Second, blood pressure should be under good control. Among many anti-hypertensive drugs available nowadays, ACE inhibitors/ARBs (Ramipril, Losartan etc) are the best if kidneys are damaged and are secreting protein. Over a long period of time, these drugs decrease protein in the urine and decrease kidney dysfunction.
Third, blood cholesterol and triglycerides (another form of fat in the blood) should be brought down drastically. These blood fats cause clotting, which may involve heart and kidneys, thus decreasing blood flow in these vital organs. Drugs which could do this job are called statins (e.g., atorvastatin), which are anyway essential in any patient with diabetes.
Diet and exercise matter a lot. Excess protein will harm the kidneys. At no point of time, patients should have very low protein diets since this will lower already low blood protein levels in the body and increase the weakness of muscles and bones. Hence protein intake must be formulated carefully and differently for each patient in conjunction with a nutrition.
There are many other factors which injure kidneys and some of these are particularly prevalent in India. Use of alternative medicines (some contain heavy metals which severely harm kidneys), infections, gastroenteritis, extreme heat, abuse of painkillers, excessive alcohol intake and high uric acid, all should be avoided/treated at all costs. All obese patients must lose weight to improve kidney functions.
Kidneys in patients with diabetes need special care. Once injured, repair is possible. Early warning for serious kidney dysfunction is given the urine test “microalbuminuria,” which should be done yearly in every patient with diabetes. The presence of this small amount of protein in urine should initiate individualised diet, exercise, loss of weight, strict control of blood sugar, blood pressure and lipids and use of kidney-benefitting drugs.
(The author is Padma Shree awardee and author of the book Diabetes with Delight)