Jereme Sylvain
Executive Vice President and Chief Financial Officer at DexCom
Thank you, Kevin. As a reminder, unless otherwise noted, the financial metrics presented today will be discussed on a non- GAAP basis. Reconciliations to GAAP can be found in today's earnings release, as well as the slide deck on our IR website. For the second quarter of 2024, we reported worldwide revenue of $1.004 billion, compared to $871.3 million in the second quarter of 2023, representing growth of 15% on a reported basis and 16% on an organic basis.
As a reminder, our definition of organic revenue excludes the impact of foreign exchange in addition to non-CGM revenue acquired or divested in the trailing twelve months. US revenue totaled $732 million for the second quarter, compared to $617 million in the second quarter of 2023, representing growth of 19%.
As Kevin mentioned, we experienced lower than expected new customer starts in conjunction with our sales force expansion and realignment, particularly in the DME channel, as well as a near-term impact from pharmacy eligibility changes, which lowered our revenue per customer relative to our expectation.
Together, these dynamics adversely impacted our revenue this quarter by approximately $40 million, as compared to our internal estimate. Based on the compounding effect of these lower second quarter new customer starts, we also expect our growth rate in the back half of the year to be impacted. To offset this, our team is working aggressively to improve our execution and deliver the higher market share levels that we believe our product deserves.
International revenue grew 7%, totaling $272 million in the second quarter. International organic revenue growth was 10% for the second quarter. While we anticipated our international growth to slow this quarter as we lapped our very strong performance from Q2 2023, our results came in lighter than expected. Our miss on new customers impacted us by approximately $10 million on the quarter.
Our international performance can often ebb and flow based on coverage decision and distributor purchases, but as Kevin mentioned, there remains a long runway ahead for DexCom CGM globally. We continue to invest in infrastructure to expand our geographical presence, provide compelling evidence to expand market access in new segments of key markets and leverage our product portfolio to meet the unique needs of various customers and health systems.
Our second quarter gross profit was $638.1 million or 63.5% of revenue, which was in line with the 63.5% of revenue we delivered in the second quarter of 2023. We continued to see further migration of our customer base from G6 to G7 in the second quarter, as we finalized new pump integrations and transitioned DexCom 1 to the G7 form factor. Between this ongoing customer transition and continued ramp up of our high volume manufacturing facilities in Mesa and Malaysia, we are making steady progress towards our long-term cost targets.
Operating expenses were $442.7 million for Q2 of 2024, compared to $395.1 million in Q2 of 2023. Operating income was $195.4 million or 19.5% of revenue in the second quarter of 2024 compared to $158.4 million or 18.2% of revenue in the same quarter of 2023. Adjusted EBITDA was $283.9 million or 28.3% of revenue for the second quarter compared to $232.6 million or 26.7% of revenue for the second quarter of 2023.
Net income for the second quarter was $174.3 million or $0.43 per share. We remain in a great financial position, closing the quarter with greater than $3.1 billion of cash and cash equivalents and based on our strong cash position, consistent free cash flow generation and ongoing growth opportunities, we are announcing an authorization for a share repurchase program of up to $750 million.
Turning to guidance, starting with full year 2024, we are decreasing our revenue guidance to a range of $4.00 billion
To $4.05 billion, representing organic growth of 11% to 13% for the year. As mentioned earlier, the compounding effect of our slower than expected new customer growth in the USDME channel and international business, as well as increased pharmacy eligibility resulted in the need to recalibrate the guide.
Our updated guidance reflects these dynamics and assumes a longer ramp in productivity in our US sales force. For margins, we are reducing our non-GAAP gross profit margin guidance to approximately 63%, while maintaining our prior guidance on non-GAAP operating margin and adjusted EBITDA at approximately 20% and 29% respectively. In addition to our annual guidance, we are providing two additional data points to help investors and analysts understand some of the unique elements impacting our revised guidance in 2024.
First, the impact to new patients from our sales force initiative, combined with our revenue per customer trends that Kevin detailed will change the historical seasonality pattern that we have typically experienced. These impacts are expected to reach their peak in the third quarter, with total revenue expected to be between $975 million and $1 billion. In conjunction with this revenue outlook, we thought it'd be helpful to provide a mid-year update on our global active customer base, which we now estimate to be between 2.5 million and 2.6 million. This represents strong growth over where we finished 2023, though the growth percentage has decelerated slightly.
Our hope is these updates will provide additional visibility, as our team works to implement several of the areas of focus that we have aligned on over the past month and as our sales force continues to ramp their efficiency.
With that, we can open up the call for Q&A. Sean?