A flat yield curve typically suggests the Fed is on track to raise US interest rates, pushing yields on the short end higher, while low inflation is seen limiting longer-dated yields.
US benchmark 10-year yields also hit a nearly three-weak peak after data showed US producer prices rose a more-than- expected 0.4 percent last month after a similar gain in September, boosting the PPI 2.8 percent in the 12 months through October for the biggest annual increase in wholesale inflation in over 5-1/2 years.
Even though yields on both the two-year and the 10-year rose after the US data, the curve continued to tighten.
The yield gap between shorter-dated and longer-dated Treasuries shrank on Tuesday, with the spread between US two-year note yields and that of US 10-year notes contracting to 69.20 basis points.
The spread between five-year and 30-year yields also flattened to 76.70 basis points. That was the narrowest spread in nearly two weeks.
The flattening move started overnight and continued throughout the curve and the trend remains in place, said Justin Lederer, Treasury analyst at Cantor Fitzgerald in New York.
"The supply dynamics going into 2018 and beyond for the Treasury suggests that there is a little pressure on shorter maturities, whereas the longer end is holding in," he said.
The US Treasury plans to finance much of next year's deficit through short-term bills instead of longer-dated paper, a move that has contributed to the current curve-flattening trend, according to Action Economics.
On Friday, the yield curve steepened on technical factors and dealers reduced their holdings of longer-dated debt following the week's auctions.
Analysts said Friday's move was an aberration.
In mid-morning trading on Tuesday, the 10-year Treasury yield was at 2.378 percent, down from 2.4 percent late on Monday.
Earlier in the global session, US 10-year yields hit 2.414, the highest since late October.
The US two-year yield hit a nine-year peak just shy of 1.7 percent, up from Monday's 1.687 percent.
US 30-year bond yields, on the other hand, fell to 2.841 percent, from 2.869 percent on Monday.