Bupa UK had a 124% increase on private medical insurance profits compared to the same time last year but faced a drop in customer numbers, according to its half year results.
Underlying profit revenues soared over the previous year to £59.2m compared to £26.4m at 2012's first half, an increase of 124%.
Revenues reached £1,255.3m in the first half of 2013, compared to H1 2012 where revenues had met £1,252.4m.
Despite this, the insurer's results revealed customer numbers fell by 3% from 2.9m to 2.8m over the past year.
The insurer said overall "Performance in the UK was much improved, as revenues held steady year-on-year and profits increased as a consequence of improved claims cost management and healthcare purchasing, and savings resulting from prior year claims being lower than anticipated in Bupa Health Funding."
However, "revenues fell and customer numbers overall were 2.8% lower year-on-year, driven by the sluggish economic environment and the increasing trend towards price-led competition in what has been a contracting market" it added.
Meanwhile, the insurer said Bupa International "performed strongly" with substantial growth in customer numbers, revenue and profit.
Revenues increased by 10% from £423.9m to £464.8m and underlying profit increased by 16% from £44.0m to £51.1m over the past year.
Stuart Fletcher, chief executive of Bupa, said: "We saw an encouraging upswing in profits in the UK, as initiatives taken by our health funding business to improve claims management, began to deliver benefits."