Could Spending More Time At A ‘Target’ Weight Protect Against Kidney Failure In People With Type 2 Diabetes?

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Type 2 diabetes and elevated weight carry many health risks, with both being independently associated with a higher risk of kidney disease (read on obesity and kidney disease here). There are many important strategies to protect the kidneys of people with type 2 diabetes, including good long term blood sugar control and blood pressure control.

Can a longer time at a target weight loss protect kidney function and protect against kidney failure in people with type 2 diabetes?

A recent study addressed this question using data from the LOOK AHEAD trial, which was a study of intensive lifestyle intervention versus standard diabetes care in people with type 2 diabetes. The intensive lifestyle group received a program of reduced calorie intake and increased exercise, aimed at achieving at least 7% weight loss, while the standard care group received usual diabetes care and lifestyle support. They included 3601 people who had good kidney function at the beginning of the study (defined as a glomerular function rate (GFR) of 60 ml/min/1.73m² or greater). They looked at the proportion of time during the first 4 years of the study that body weight was at a weight loss target of at least 7% lower than the start of the study. The point of this analysis was to see whether having a higher amount of time at this target weight loss reduced the risk of a composite end point of end-stage kidney disease or GFR decline of at least 30% from baseline to a level less than 60.

During a median follow-up of 8 years, they found that the more time that a participant spent at their target weight, the lower the risk of a poor kidney outcome. They found that, compared to people who spent 0% of time at target weight:

If they spent 70 to 100% of the study time at their target weight, they had a 46% reduction in risk of having a poor kidney outcome.
If they spent 30 to 70% of the time at target weight, they had a 29% reduction in risk
If they spent 0 to 30% of the study time at target weight, they had a 27% reduction in risk

The original LOOK AHEAD trial analysis of kidney health showed that intensive lifestyle intervention reduced the incidence of very high risk chronic kidney disease by 31%, with the benefit partially attributable to reduction in weight, A1C (diabetes report card), and blood pressure. However, a subset of people in the intensive lifestyle group regained weight within the first year and returned to their baseline weight by 3 to 5 years. (Regain of weight after lifestyle-induced weight loss is common, due to our natural human biology that vigorously defends against weight loss and promotes weight regain – more on this here and here) . In fact, 26% of people in the intensive lifestyle group weighed more at 4 years than they did at the start of the study. We can speculate from this new analysis that spending a higher amount of time at a target weight may have more benefits for kidney health.

In clinical practice, we typically do not set targets for weight loss, putting the focus on improving health. We do look at weight loss in clinical trials of lifestyle modification, medications, and bariatric surgery, but we tend to look at the amount of weight loss, and not so much the percentage of time that a person spends at a certain weight. It is really interesting that the current study uses a non-traditional approach of evaluating outcomes based on how much time was spent at a certain weight target, as this looks beyond only how much weight was lost, incorporating both average body weight and weight variability.

BOTTOM LINE: Lifestyle intervention targeted at weight loss protects the kidneys of people with type 2 diabetes. This study suggests that a longer time spent at a target weight loss gives greater benefit to protect the kidneys in people with type 2 diabetes. It would be interesting to incorporate time at target weight more routinely as part of the assessment of weight management interventions.

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