Qt renders text with different antialiasing algorithm(sometimes uses ClearType) on same font with different font size

Qt seems to render text with different antialiasing algorithms depending of font size. The problem is on windows platform only(Linux is ok).

for example:
Arial 48 is drawed with grayscale antialiasing algorithm.
while
Arial 47 is drawed with cleartype antialiasing algorithm.

Solution should be:
All text should be antialiased with grayscale method(just like it's in other platforms), unless explicitly specified otherwise.

Here is code sample:

void Widget::paintEvent(QPaintEvent * event)
{
Q_UNUSED(event);
QPainter painter(this);
painter.setFont(m_font);
painter.setRenderHints(QPainter::Antialiasing | QPainter::TextAntialiasing);
painter.drawText(10, 80, "Some text.");
}

where m_font can be set as:
m_font = QFont("Arial", 47, 25);
or
m_font = QFont("Arial", 48, 25);

I have attached small demo app that shows the problem, and printscreen of that app drawing text in Arial size 47, and size 48.