Moderate healthy habits linked to better diabetes control than the highest scores in Iranian study

A national Iranian survey found that people with moderate lifestyle scores had better glucose indicators than those with the lowest scores, but no clear extra benefit among those with the highest scores.

Researchers in Tehran have found that everyday health habits are linked to better glucose control in adults with diabetes, but not in a simple straight line. The study, published in BMJ Open and based on Iran’s 2021 national STEPS survey, suggests that people with a moderate level of healthy behaviour had better blood sugar indicators than those with the lowest scores, while the strongest overall lifestyle scores did not produce a further clear advantage. That pattern has prompted the authors to caution against reading the results as a straightforward “more is always better” message.

The analysis drew on laboratory and survey data from 3,042 adults aged 25 and over with diabetes identified through the national risk-factor surveillance system. Diabetes was defined using fasting blood glucose, HbA1c or use of glucose-lowering medication. The researchers then created a composite lifestyle index, or CLI, combining diet, physical activity, smoking and alcohol use, and split participants into low, moderate and high groups according to their scores.

In the fully adjusted analysis, the moderate group recorded lower fasting glucose and HbA1c than the lowest lifestyle group. The report published by BMJ Open said the difference amounted to about 7.36 mg/dL less fasting glucose and 0.27 percentage points less HbA1c, alongside a 1.37-fold higher chance of achieving good glycaemic control, defined as HbA1c below 7%. But the highest lifestyle group did not outperform the moderate group, and the statistics pointed to a U-shaped relationship rather than a linear one.

That finding does not mean highly healthy habits are harmful. The authors argued instead that the result may reflect the complexity of diabetes management in real life, where people with more advanced disease may already have been encouraged to overhaul their behaviour, making cause and effect difficult to disentangle in a cross-sectional study. They said longer-term research is needed before any firm conclusions can be drawn about how different intensities of lifestyle change influence blood sugar over time.

The study also sits within a wider Iranian public-health picture in which awareness of diabetes has improved, but control remains limited. A separate analysis of the country’s STEPS surveys from 2007, 2011, 2016 and 2021, published in Diabetes Research and Clinical Practice, found that awareness rose from 53.5% in 2004 to 73.3% in 2021, while the share of patients with adequate control increased from 14.5% to 28%. Even so, that still leaves a large proportion of people living with diabetes without optimal glucose management.

One of the more striking patterns in the new work was the difference between people who knew they had diabetes and those who did not. Among participants unaware of their condition, better lifestyle scores were associated with lower fasting glucose and HbA1c. Among those already diagnosed, the trend was less consistent, suggesting that diagnosis, treatment and behaviour may interact in ways that are not captured by a single lifestyle score. Taken together, the findings point to a familiar but stubborn message in diabetes care: medication matters, but so do diet, movement and smoking avoidance, and public-health gains depend on improving all of them at once.