Being married may help prevent type 2 diabetes, regardless of whether the relationship is happy, research suggests.

Previous studies have found that happy marriages confer a range of health benefits compared with being single, including a longer life, fewer strokes and heart attacks, less depression and healthier eating.

Now a new study has looked at blood sugar levels in older people in particular, finding that being married or living together helps keep sugar levels under control.

The findings appeared to hold true regardless of whether the relationship was happy or under strain.

Experts from the University of Luxembourg and the University of Ottawa in Canada examined data from the English Longitudinal Study of Ageing on 3335 adults aged 50 to 89 who did not have diabetes at the start of the study.

They published their findings in the journal BMJ Open Diabetes Research & Care.

The study included data gathered from blood samples which measured HbA1c (average blood glucose) levels.

People were asked if they had a husband, wife, or partner with whom they lived and were asked questions to examine the level of strain and support within the relationship.

The data showed that 76 per cent of people in the analysis were married or living together.

Researchers found that the quality of the relationship did not make a significant difference to the average levels of blood glucose, suggesting that having a supportive or strained relationship was less important than just having a relationship at all.

"Overall, our results suggested that marital/cohabitating relationships were inversely related to HbA1c levels regardless of dimensions of spousal support or strain," the researchers concluded.

"Likewise, these relationships appeared to have a protective effect against HbA1c levels above the pre-diabetes threshold."