In the rural district of Agincourt in northeastern South Africa, every family knows when the government payment arrives. For some it is an old-age pension, for others a child grant. The money is small, about 21 dollars per person per month, but for local residents it is a trickle that keeps the household budget from running dry. Scientists decided to check whether that trickle affects blood sugar, since diabetes is spreading here faster than almost anywhere else.
For seven years, researchers followed 4580 adults. They measured glucose levels first, then measured them again. In parallel, they reconstructed the month-by-month payment history for each household going back to 2000. A picture emerged: who received how much money, and how their blood sugar changed along the way. It turned out that every additional hundred rand per month (about 6 dollars) lowered the risk of prediabetes by 6%. Prediabetes is a borderline state in which blood sugar is already above normal but not yet diabetic. That is the threshold the payments hold people back from crossing.
The trickle does not put out a fire, but it keeps the fire from flaring up. If diabetes has already begun, money is no substitute for medicine. But if blood sugar has only started creeping upward, regular assistance helps bring it back to normal. It is a bit like steady light watering saving a garden in a drought: it will not refill a dried-up lake, but it will keep the seedlings alive.
Until now, no one knew whether cash payments could affect diabetes in middle-income countries. Now it is clear: they can, but only at an early stage. This matters for officials who design social programs. Even small sums, if they arrive regularly, pay off in health. The study does not say what exactly changes: diet, physical activity, or stress. But it shows that economic support is not just charity, it is a prevention tool that works at the level of blood sugar.
The highest glucose level recorded in the study was 30.6 mmol/L, which is three times the diabetes threshold and life-threatening. Yet the average payment per person was only about 21 dollars a month, less than the cost of a single doctor's visit in developed countries.
Not published on arXiv. Here are its page, the PDF and the formalization: you can check it yourself, not only read our account.