Tandem Diabetes Care, Inc.’s TNDM adjusted net loss of 7 cents for first-quarter 2021 was narrower than the year-ago adjusted net loss of 22 cents. However, the metric surpassed the Zacks Consensus Estimate of a loss of 15 cents.GAAP net loss for the quarter was 8 cents, narrower than the year-ago net loss of 25 cents.RevenuesRevenues in the quarter came in at $141 million, beating the Zacks Consensus Estimate by 14.9%. The top line surged 44% year over year despite sales pressure due to COVID-19. Robust adoption of the company’s Control-IQ technology significantly boosted the top line in the reported quarter.Quarter in DetailTandem Diabetes registered international sales of $37.7 million in the quarter under review, recording a 105% rise from first-quarter 2020. Domestic sales came in at $103.3 million, up 30% year on year.International pump shipments surged 106% to 8,708 pumps. Domestic pump shipments jumped 26% year over year to 16,644 units.Tandem Diabetes Care, Inc. Price, Consensus and EPS Surprise Tandem Diabetes Care, Inc. price-consensus-eps-surprise-chart | Tandem Diabetes Care, Inc. QuoteThe company believes that surge in pump shipments resulted from the continued momentum of its Control-IQ technology.MarginsGross profit in the first quarter was $73.3 million, marking 45.8% year-over-year growth. Gross margin was, however, 51.9%, indicating an expansion of 64 basis points (bps).Selling, general and administrative expenses rose 17.8% to $58.6 million in the quarter under review. Research and development expenses also increased 27.2% to $17.9 million.Overall operating loss was $3.2 million, compared with the year-ago loss of $13.5 million.Financial PositionTandem Diabetes exited first-quarter 2021 with cash and cash equivalents, and short-term investments of $513.4 million compared with $484.9 million at the end of 2020.2021 Guidance RaisedThe company has updated its guidance for 2021.For 2021, the sales projection has been raised to $625-$640 million, indicating annual sales growth of 25% to 28%. The company’s prior sales guidance for 2021 was in the range of $600-$615 million. The Zacks Consensus Estimate for 2021 revenues is pegged at $610.4 million.Full-year international sales are expected in the range of $125-$130 million, which suggests annual sales growth of 50% to 56%. This also represents a significant improvement from the prior guidance of $105-$110 million.Our TakeTandem Diabetes delivered better-than-expected results for the first quarter of 2021. The robust top-line growth despite pandemic-led business disruptions is impressive. Strong domestic and international pump sales along with robust domestic and international pump shipments buoy optimism. Continued strength in demand for t:slim X2 insulin pumps across the globe and rising customer adoption of the company’s Control-IQ technology looks encouraging. Expansion of both margins and a raised 2021 sales forecast bode well for the stock.However, the unabated spread of coronavirus continues to pose challenges to the company’s operations. The company’s incurring of operating loss is discouraging as well.Zacks Rank and Other Key PicksTandem Diabetes currently carries a Zacks Rank #2 (Buy).A few similar-ranked stocks in the broader medical space are Boston Scientific Corporation BSX, Illumina, Inc. ILMN and HCA Healthcare, Inc. HCA. You can see the complete list of today’s Zacks #1 Rank (Strong Buy) stocks here.Boston Scientific reported first-quarter 2021 adjusted earnings per share (EPS) of 37 cents, beating the Zacks Consensus Estimate by 23.3%. Net revenues of $2.75 billion outpaced the consensus estimate by 5.3%.Illumina reported first-quarter 2021 adjusted EPS of $1.89, beating the Zacks Consensus Estimate by 38.9%. Revenues of $1.09 billion outpaced the consensus estimate of $1.08 billion.HCA Healthcare reported first-quarter 2021 adjusted EPS of $4.14, surpassing the Zacks Consensus Estimate by 23.6%. Net revenues of $14 billion exceeded the Zacks Consensus Estimate by 2.2%.Zacks Top 10 Stocks for 2021In addition to the stocks discussed above, would you like to know about our 10 best buy-and-hold tickers for the entirety of 2021?Last year's 2020 Zacks Top 10 Stocks portfolio returned gains as high as +386.8%. Now a brand-new portfolio has been handpicked from over 4,000 companies covered by the Zacks Rank. Don’t miss your chance to get in on these long-term buys.Access Zacks Top 10 Stocks for 2021 today >>Want the latest recommendations from Zacks Investment Research? Today, you can download 7 Best Stocks for the Next 30 Days. Click to get this free report Illumina, Inc. (ILMN): Free Stock Analysis Report Boston Scientific Corporation (BSX): Free Stock Analysis Report HCA Healthcare, Inc. (HCA): Free Stock Analysis Report Tandem Diabetes Care, Inc. (TNDM): Free Stock Analysis Report To read this article on Zacks.com click here.